diff --git a/addons/point_of_sale/point_of_sale.py b/addons/point_of_sale/point_of_sale.py
index 2e5b4c1ffd8..7d608a73a7b 100644
--- a/addons/point_of_sale/point_of_sale.py
+++ b/addons/point_of_sale/point_of_sale.py
@@ -706,6 +706,7 @@ class pos_order(osv.osv):
         @return: True
         """
         stock_picking_obj = self.pool.get('stock.picking')
+        wf_service = netsvc.LocalService("workflow")
         for order in self.browse(cr, uid, ids, context=context):
             wf_service.trg_validate(uid, 'stock.picking', order.picking_id.id, 'button_cancel', cr)
             if stock_picking_obj.browse(cr, uid, order.picking_id.id, context=context).state <> 'cancel':