I have created a cron job to update account.resource object every day using 'write' :

1. search for the resource
2. update the resource

exist = self.pool.get('account.resource').search(cr, uid, [('resource_ID', '=', some_id)], context=context) 
print exist
if len(exist) != 0:
          print 'resource found'
          res = self.pool.get('account.resource').write(cr, uid,exist,{'status': 'done', })                        
          print res

In my console I got

[7]
resource found
none

OpenERP finds the resource but doesn't update it any idea?