diff --git a/admin-dev/themes/template/orders/_discount_form.tpl b/admin-dev/themes/template/orders/_discount_form.tpl
new file mode 100644
index 000000000..ee8880223
--- /dev/null
+++ b/admin-dev/themes/template/orders/_discount_form.tpl
@@ -0,0 +1,52 @@
+<form method="POST" action="{$currentIndex}&viewOrder&id_order={$smarty.get.id_order|escape:'htmlall':'UTF-8'}&token={$smarty.get.token|escape:'htmlall':'UTF-8'}">
+	<label>{l s='Name'}</label>
+	<div class="margin-form">
+		<input type="text" name="discount_name" value="" />
+	</div>
+
+	<label>{l s='Type'}</label>
+	<div class="margin-form">
+		<select name="discount_type" id="discount_type">
+			<option value="1">{l s='Percent'}</option>
+			<option value="2">{l s='Amount'}</option>
+			<option value="3">{l s='Free shipping'}</option>
+		</select>
+	</div>
+
+	<div id="discount_value_field">
+		<label>{l s='Value'}</label>
+		<div class="margin-form">
+			{if ($currency->format % 2)}
+				<span id="discount_currency_sign" style="display: none;">{$currency->sign}</span>
+			{/if}
+			<input type="text" name="discount_value" size="3" />
+			{if !($currency->format % 2)}
+				<span id="discount_currency_sign" style="display: none;">{$currency->sign}</span>
+			{/if}
+			<span id="discount_percent_symbol">%</span>
+			<p class="preference_description" id="discount_value_help" style="width: 95%;display: none;">
+				{l s='This value must be taxes included.'}
+			</p>
+		</div>
+	</div>
+
+	{if $order->hasInvoice()}
+	<label>{l s='Invoice'}</label>
+	<div class="margin-form">
+		<select name="discount_invoice">
+			{foreach from=$invoices_collection item=invoice}
+				<option value="{$invoice->id}" selected="selected">{$invoice->getInvoiceNumberFormatted($current_id_lang)} - {displayPrice price=$invoice->total_paid_tax_incl currency=$order->id_currency}</option>
+			{/foreach}
+		</select><br />
+		<input type="checkbox" name="discount_all_invoices" id="discount_all_invoices" value="1" /> <label class="t" for="discount_all_invoices">{l s='Apply on all invoices'}</label>
+		<p class="preference_description" style="width: 95%">
+			{l s='If you select to create this discount for all invoices, one discount will be created per order invoice.'}
+		</p>
+	</div>
+	{/if}
+
+	<p class="center">
+		<input class="button" type="submit" name="submitNewVoucher" value="{l s='Add'}" />&nbsp;
+		<a href="#" id="cancel_add_voucher">{l s='Cancel'}</a>
+	</p>
+</form>
\ No newline at end of file
diff --git a/admin-dev/themes/template/orders/_documents.tpl b/admin-dev/themes/template/orders/_documents.tpl
index f1a2af478..ad023f470 100644
--- a/admin-dev/themes/template/orders/_documents.tpl
+++ b/admin-dev/themes/template/orders/_documents.tpl
@@ -15,7 +15,7 @@
 	{*/if*}
 		<td class="document_date">{dateFormat date=$document->date_add}</td>
 		<td class="document_type">Invoice</td>
-		<td class="document_number"><a href="pdf.php?pdf&id_order_invoice={$document->id}">#{Configuration::get('PS_INVOICE_PREFIX', $current_id_lang)}{'%06d'|sprintf:$document->number}</a></td>
+		<td class="document_number"><a href="pdf.php?pdf&id_order_invoice={$document->id}">{$document->getInvoiceNumberFormatted($current_id_lang)}</a></td>
 		<td class="document_amount">
 		{*if TYPE DOCUMENT = INVOICE *}
 			{displayPrice price=$document->total_paid_tax_incl currency=$currency->id}&nbsp;
diff --git a/admin-dev/themes/template/orders/_new_product.tpl b/admin-dev/themes/template/orders/_new_product.tpl
index 5f5f8411b..5ebeeaa75 100644
--- a/admin-dev/themes/template/orders/_new_product.tpl
+++ b/admin-dev/themes/template/orders/_new_product.tpl
@@ -24,7 +24,7 @@
 		<select name="add_product[invoice]" id="add_product_product_invoice" disabled="disabled">
 			<optgroup class="existing" label="{l s='Existing'}">
 				{foreach from=$invoices_collection item=invoice}
-				<option value="{$invoice->id}">#{Configuration::get('PS_INVOICE_PREFIX', $current_id_lang)}{'%06d'|sprintf:$invoice->number}</option>
+				<option value="{$invoice->id}">{$invoice->getInvoiceNumberFormatted($current_id_lang)}</option>
 				{/foreach}
 			</optgroup>
 			<optgroup label="{l s='New'}">
diff --git a/admin-dev/themes/template/orders/view.tpl b/admin-dev/themes/template/orders/view.tpl
index c636d41bd..cadc69a6c 100755
--- a/admin-dev/themes/template/orders/view.tpl
+++ b/admin-dev/themes/template/orders/view.tpl
@@ -231,7 +231,7 @@
 								<td>{displayPrice price=$payment->amount currency=$payment->id_currency}</td>
 								<td>
 								{if $payment->id_order_invoice}
-									#{Configuration::get('PS_INVOICE_PREFIX', $current_id_lang)}{'%06d'|sprintf:OrderInvoice::retrieveOneById($payment->id_order_invoice)->number}
+									{OrderInvoice::retrieveOneById($payment->id_order_invoice)->getInvoiceNumberFormatted($current_id_lang)}
 								{else}
 									{l s='No invoice'}
 								{/if}
@@ -270,7 +270,7 @@
 									<td>
 										<select name="payment_invoice" id="payment_invoice">
 										{foreach from=$not_paid_invoices_collection item=invoice}
-											<option value="{$invoice->id}" selected="selected">#{Configuration::get('PS_INVOICE_PREFIX', $current_id_lang)}{'%06d'|sprintf:$invoice->number}</option>
+											<option value="{$invoice->id}" selected="selected">{$invoice->getInvoiceNumberFormatted($current_id_lang)}</option>
 										{/foreach}
 										</select>
 									</td>
@@ -570,56 +570,7 @@
 						</tr>
 						<tr style="display: none" >
 							<td colspan="3" class="current-edit" id="voucher_form">
-								<form method="POST" action="{$currentIndex}&viewOrder&id_order={$smarty.get.id_order|escape:'htmlall':'UTF-8'}&token={$smarty.get.token|escape:'htmlall':'UTF-8'}">
-									<label>{l s='Name'}</label>
-									<div class="margin-form">
-										<input type="text" name="discount_name" value="" />
-									</div>
-
-									<label>{l s='Type'}</label>
-									<div class="margin-form">
-										<select name="discount_type" id="discount_type">
-											<option value="1">{l s='Percent'}</option>
-											<option value="2">{l s='Amount'}</option>
-											<option value="3">{l s='Free shipping'}</option>
-										</select>
-									</div>
-
-									<div id="discount_value_field">
-										<label>{l s='Value'}</label>
-										<div class="margin-form">
-											{if ($currency->format % 2)}
-												<span id="discount_currency_sign" style="display: none;">{$currency->sign}</span>
-											{/if}
-											<input type="text" name="discount_value" size="3" />
-											{if !($currency->format % 2)}
-												<span id="discount_currency_sign" style="display: none;">{$currency->sign}</span>
-											{/if}
-											<span id="discount_percent_symbol">%</span>
-											<p class="preference_description" id="discount_value_help" style="width: 95%;display: none;">
-												{l s='This value must be taxes included.'}
-											</p>
-										</div>
-									</div>
-
-									<label>{l s='Invoice'}</label>
-									<div class="margin-form">
-										<select name="discount_invoice">
-											{foreach from=$invoices_collection item=invoice}
-												<option value="{$invoice->id}" selected="selected">#{Configuration::get('PS_INVOICE_PREFIX', $current_id_lang)}{'%06d'|sprintf:$invoice->number} - {displayPrice price=$invoice->total_paid_tax_incl currency=$order->id_currency}</option>
-											{/foreach}
-										</select><br />
-										<input type="checkbox" name="discount_all_invoices" id="discount_all_invoices" value="1" /> <label class="t" for="discount_all_invoices">{l s='Apply on all invoices'}</label>
-										<p class="preference_description" style="width: 95%">
-											{l s='If you select to create this discount for all invoices, one discount will be created per order invoice.'}
-										</p>
-									</div>
-
-									<p class="center">
-										<input class="button" type="submit" name="submitNewVoucher" value="{l s='Add'}" />&nbsp;
-										<a href="#" id="cancel_add_voucher">{l s='Cancel'}</a>
-									</p>
-								</form>
+								{include file='orders/_discount_form.tpl'}
 							</td>
 						</tr>
 					{/if}
diff --git a/classes/order/OrderInvoice.php b/classes/order/OrderInvoice.php
index da7d4b4c1..b9780f218 100644
--- a/classes/order/OrderInvoice.php
+++ b/classes/order/OrderInvoice.php
@@ -332,9 +332,11 @@ class OrderInvoiceCore extends ObjectModel
 			foreach ($taxes_infos as $tax_infos)
 			{
 				if (!isset($tmp_tax_infos[$tax_infos['rate']]))
-					$tmp_tax_infos[$tax_infos['rate']] = array('total_amount' => 0,
-																'name' => 0,
-																'total_price_tax_excl' => 0);
+					$tmp_tax_infos[$tax_infos['rate']] = array(
+						'total_amount' => 0,
+						'name' => 0,
+						'total_price_tax_excl' => 0
+					);
 
 				$tmp_tax_infos[$tax_infos['rate']]['total_amount'] += $tax_infos['total_amount'];
 				$tmp_tax_infos[$tax_infos['rate']]['name'] = $tax_infos['name'];
@@ -506,4 +508,15 @@ class OrderInvoiceCore extends ObjectModel
 		$order_payments->where('id_order_invoice', '=', $this->id);
 		return $order_payments;
 	}
+
+	/**
+	 * Get the formatted number of invoice
+	 * @since 1.5.0.2
+	 * @param int $id_lang for invoice_prefix
+	 * @return string
+	 */
+	public function getInvoiceNumberFormatted($id_lang)
+	{
+		return '#'.Configuration::get('PS_INVOICE_PREFIX', $id_lang).sprintf('%06d', $this->number);
+	}
 }
\ No newline at end of file
diff --git a/controllers/admin/AdminOrdersController.php b/controllers/admin/AdminOrdersController.php
index 82b871d79..0fce85607 100755
--- a/controllers/admin/AdminOrdersController.php
+++ b/controllers/admin/AdminOrdersController.php
@@ -434,9 +434,9 @@ class AdminOrdersControllerCore extends AdminController
 
 								// @since 1.5.0 : Advanced Stock Management
 								$product_to_inject = new Product($order_detail->product_id, false, $this->context->language->id, $order->id_shop);
-								
+
 								$product = new Product($order_detail->product_id);
-								
+
 								if (Configuration::get('PS_ADVANCED_STOCK_MANAGEMENT')
 									&& $product->advanced_stock_management
 									&& $order_detail->id_warehouse != 0
@@ -788,12 +788,15 @@ class AdminOrdersControllerCore extends AdminController
 				if (!Validate::isLoadedObject($order))
 					throw new PrestashopException('Can\'t load Order object');
 
-				// If the discount is for only one invoice
-				if (!Tools::isSubmit('discount_all_invoices'))
+				if ($order->hasInvoice())
 				{
-					$order_invoice = new OrderInvoice(Tools::getValue('discount_invoice'));
-					if (!Validate::isLoadedObject($order_invoice))
-						throw new PrestashopException('Can\'t load Order Invoice object');
+					// If the discount is for only one invoice
+					if (!Tools::isSubmit('discount_all_invoices'))
+					{
+						$order_invoice = new OrderInvoice(Tools::getValue('discount_invoice'));
+						if (!Validate::isLoadedObject($order_invoice))
+							throw new PrestashopException('Can\'t load Order Invoice object');
+					}
 				}
 
 				$cart_rules = array();
@@ -809,14 +812,9 @@ class AdminOrdersControllerCore extends AdminController
 								$cart_rules[$order_invoice->id]['value_tax_excl'] = Tools::ps_round($order_invoice->total_paid_tax_excl * Tools::getValue('discount_value') / 100, 2);
 
 								// Update OrderInvoice
-								$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-
-								$order_invoice->update();
+								$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
 							}
-							else
+							elseif ($order->hasInvoice())
 							{
 								$order_invoices_collection = $order->getInvoicesCollection();
 								foreach($order_invoices_collection as $order_invoice)
@@ -825,13 +823,14 @@ class AdminOrdersControllerCore extends AdminController
 									$cart_rules[$order_invoice->id]['value_tax_excl'] = Tools::ps_round($order_invoice->total_paid_tax_excl * Tools::getValue('discount_value') / 100, 2);
 
 									// Update OrderInvoice
-									$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-									$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-									$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-									$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-									$order_invoice->update();
+									$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
 								}
 							}
+							else
+							{
+								$cart_rules[0]['value_tax_incl'] = Tools::ps_round($order->total_paid_tax_incl * Tools::getValue('discount_value') / 100, 2);
+								$cart_rules[0]['value_tax_excl'] = Tools::ps_round($order->total_paid_tax_excl * Tools::getValue('discount_value') / 100, 2);
+							}
 						}
 						else
 							$this->_errors[] = Tools::displayError('Discount value is invalid');
@@ -848,29 +847,34 @@ class AdminOrdersControllerCore extends AdminController
 								$cart_rules[$order_invoice->id]['value_tax_excl'] = Tools::ps_round(Tools::getValue('discount_value') / (1 + ($order->getTaxesAverageUsed() / 100)), 2);
 
 								// Update OrderInvoice
-								$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->update();
+								$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
 							}
 						}
-						else
+						elseif ($order->hasInvoice())
 						{
 							$order_invoices_collection = $order->getInvoicesCollection();
 							foreach($order_invoices_collection as $order_invoice)
 							{
 								if (Tools::getValue('discount_value') > $order_invoice->total_paid_tax_incl)
-									continue;
-								$cart_rules[$order_invoice->id]['value_tax_incl'] = Tools::ps_round(Tools::getValue('discount_value'), 2);
-								$cart_rules[$order_invoice->id]['value_tax_excl'] = Tools::ps_round(Tools::getValue('discount_value') / (1 + ($order->getTaxesAverageUsed() / 100)), 2);
+									$this->_errors[] = Tools::displayError('Discount value is superior than the order invoice total (Invoice: ').$order_invoice->getInvoiceNumberFormatted(Context::getContext()->language->id).')';
+								else
+								{
+									$cart_rules[$order_invoice->id]['value_tax_incl'] = Tools::ps_round(Tools::getValue('discount_value'), 2);
+									$cart_rules[$order_invoice->id]['value_tax_excl'] = Tools::ps_round(Tools::getValue('discount_value') / (1 + ($order->getTaxesAverageUsed() / 100)), 2);
 
-								// Update OrderInvoice
-								$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->update();
+									// Update OrderInvoice
+									$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
+								}
+							}
+						}
+						else
+						{
+							if (Tools::getValue('discount_value') > $order->total_paid_tax_incl)
+								$this->_errors[] = Tools::displayError('Discount value is superior than the order total');
+							else
+							{
+								$cart_rules[0]['value_tax_incl'] = Tools::ps_round(Tools::getValue('discount_value'), 2);
+								$cart_rules[0]['value_tax_excl'] = Tools::ps_round(Tools::getValue('discount_value') / (1 + ($order->getTaxesAverageUsed() / 100)), 2);
 							}
 						}
 						break;
@@ -884,14 +888,10 @@ class AdminOrdersControllerCore extends AdminController
 								$cart_rules[$order_invoice->id]['value_tax_excl'] = $order_invoice->total_shipping_tax_excl;
 
 								// Update OrderInvoice
-								$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->update();
+								$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
 							}
 						}
-						else
+						elseif ($order->hasInvoice())
 						{
 							$order_invoices_collection = $order->getInvoicesCollection();
 							foreach($order_invoices_collection as $order_invoice)
@@ -902,11 +902,7 @@ class AdminOrdersControllerCore extends AdminController
 								$cart_rules[$order_invoice->id]['value_tax_excl'] = $order_invoice->total_shipping_tax_excl;
 
 								// Update OrderInvoice
-								$order_invoice->total_discount_tax_incl += $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_discount_tax_excl += $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->total_paid_tax_incl -= $cart_rules[$order_invoice->id]['value_tax_incl'];
-								$order_invoice->total_paid_tax_excl -= $cart_rules[$order_invoice->id]['value_tax_excl'];
-								$order_invoice->update();
+								$this->applyDiscountOnInvoice($order_invoice, $cart_rules[$order_invoice->id]['value_tax_incl'], $cart_rules[$order_invoice->id]['value_tax_excl']);
 							}
 						}
 						break;
@@ -990,12 +986,12 @@ class AdminOrdersControllerCore extends AdminController
 
 		// gets warehouses to ship products, if and only if advanced stock management is activated
 		$warehouse_list = null;
-		
+
 		$order_details = $order->getOrderDetailList();
 		foreach ($order_details as $order_detail)
 		{
 			$product = new Product($order_detail['product_id']);
-			
+
 			if (Configuration::get('PS_ADVANCED_STOCK_MANAGEMENT')
 				&& $product->advanced_stock_management
 			)
@@ -1354,7 +1350,7 @@ class AdminOrdersControllerCore extends AdminController
 		$invoice_array = array();
 		foreach($invoice_collection as $invoice)
 		{
-			$invoice->name = '#'.Configuration::get('PS_INVOICE_PREFIX', Context::getContext()->language->id).sprintf('%06d', $invoice->number);
+			$invoice->name = $invoice->getInvoiceNumberFormatted(Context::getContext()->language->id);
 			$invoice_array[] = $invoice;
 		}
 
@@ -1377,7 +1373,8 @@ class AdminOrdersControllerCore extends AdminController
 			'order' => $order,
 			'invoices' => $invoice_array,
 			'documents_html' => $this->context->smarty->fetch('orders/_documents.tpl'),
-			'shipping_html' => $this->context->smarty->fetch('orders/_shipping.tpl')
+			'shipping_html' => $this->context->smarty->fetch('orders/_shipping.tpl'),
+			'discount_form_html' => $this->context->smarty->fetch('orders/_discount_form.tpl')
 		)));
 	}
 
@@ -1518,7 +1515,7 @@ class AdminOrdersControllerCore extends AdminController
 		$invoice_array = array();
 		foreach($invoice_collection as $invoice)
 		{
-			$invoice->name = '#'.Configuration::get('PS_INVOICE_PREFIX', Context::getContext()->language->id).sprintf('%06d', $invoice->number);
+			$invoice->name = $invoice->getInvoiceNumberFormatted(Context::getContext()->language->id);
 			$invoice_array[] = $invoice;
 		}
 
@@ -1584,7 +1581,7 @@ class AdminOrdersControllerCore extends AdminController
 		$invoice_array = array();
 		foreach($invoice_collection as $invoice)
 		{
-			$invoice->name = '#'.Configuration::get('PS_INVOICE_PREFIX', Context::getContext()->language->id).sprintf('%06d', $invoice->number);
+			$invoice->name = $invoice->getInvoiceNumberFormatted(Context::getContext()->language->id);
 			$invoice_array[] = $invoice;
 		}
 
@@ -1708,5 +1705,15 @@ class AdminOrdersControllerCore extends AdminController
 
 		return $products;
 	}
+
+	protected function applyDiscountOnInvoice($order_invoice, $value_tax_incl, $value_tax_excl)
+	{
+		// Update OrderInvoice
+		$order_invoice->total_discount_tax_incl += $value_tax_incl;
+		$order_invoice->total_discount_tax_excl += $value_tax_excl;
+		$order_invoice->total_paid_tax_incl -= $value_tax_incl;
+		$order_invoice->total_paid_tax_excl -= $value_tax_excl;
+		$order_invoice->update();
+	}
 }
 
diff --git a/js/admin_order.js b/js/admin_order.js
index 2beae95b7..177d4dc75 100644
--- a/js/admin_order.js
+++ b/js/admin_order.js
@@ -92,6 +92,11 @@ function updateShipping(shipping_html)
 	$('#shipping_table_old').remove();
 }
 
+function updateDiscountForm(discount_form_html)
+{
+	$('#voucher_form').html(discount_form_html);
+}
+
 function populateWarehouseList(warehouse_list)
 {
 	$('#add_product_product_warehouse_area').hide();
@@ -419,6 +424,7 @@ function init()
 							updateInvoice(data.invoices);
 							updateDocuments(data.documents_html);
 							updateShipping(data.shipping_html);
+							updateDiscountForm(data.discount_form_html);
 
 							// Initialize all events
 							init();
@@ -591,6 +597,7 @@ function init()
 						updateAmounts(data.order);
 						updateInvoice(data.invoices);
 						updateDocuments(data.documents_html);
+						updateDiscountForm(data.discount_form_html);
 
 						// Initialize all events
 						init();
@@ -665,6 +672,7 @@ function init()
 					updateAmounts(data.order);
 					updateInvoice(data.invoices);
 					updateDocuments(data.documents_html);
+					updateDiscountForm(data.discount_form_html);
 				}
 				else
 					alert(data.error);