HI EVERY BODY ,WHEN I WONT TO GENERATE A INVOICE FROM A PACKING LIST A RECEIVE THIS ERROR:
Traceback (most recent call last):
File "netsvc.pyo", line 231, in dispatch
File "netsvc.pyo", line 74, in __call__
File "service\web_services.pyo", line 552, in execute
File "service\web_services.pyo", line 532, in _execute
File "wizard\__init__.pyo", line 178, in execute
File "wizard\__init__.pyo", line 83, in execute_cr
File "C:\Program Files\OpenERP Server\addons\stock\wizard\wizard_invoice_onshipping.py", line 102, in _create_invoice
File "C:\Program Files\OpenERP Server\addons\delivery\stock.py", line 48, in action_invoice_create
File "C:\Program Files\OpenERP Server\addons\sale\stock.py", line 124, in action_invoice_create
File "C:\Program Files\OpenERP Server\addons\stock\stock.py", line 676, in action_invoice_create
TypeError: unsupported operand type(s) for +: 'bool' and 'unicode'

BECAUSE THE FIELD "REFERENCE" IS EMPTY .
CAN U HELP ME PLEASE.
THANK U