diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 30c24f7af25..6a9572b547c 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -818,6 +818,9 @@ class sale_order_line(osv.osv):
                             int(config['price_accuracy']))
                 fpos = line.order_id.fiscal_position or False
                 a = self.pool.get('account.fiscal.position').map_account(cr, uid, fpos, a)
+                if not a:
+                    raise osv.except_osv(_('Error !'),
+                                _('There is no income category account defined in default Properties for Product Category or Fiscal Position is not defined !'))
                 inv_id = self.pool.get('account.invoice.line').create(cr, uid, {
                     'name': line.name,
                     'origin': line.order_id.name,