--- account.py  2014-05-07 07:52:32.016443000 +0200
+++ /opt/openerp/server/openerp/addons/account_vat_on_payment/account.py        2014-05-07 15:10:40.997358933 +0200
@@ -21,7 +21,7 @@
 #
 ##############################################################################

-from openerp.osv import orm, fields
+from openerp.osv import orm, fields, osv
 from tools.translate import _