Why does the backup database doesn't work on OE 6.1.1? Going to the Database manager and licking on 'backup' gives me only a 3MB dump as opposed to the 64MB. With the error message:

{"message": "OpenERP WebClient Error", "code": 300, "data": {"debug": "Client Traceback (most recent call last):\n  File \"/usr/local/lib/python2.6/dist-packages/openerp-6.1_20120828_233302-py2.6.egg/openerp/addons/web/common/http.py\", line 260, in dispatch\n    r = method(controller, self, **self.params)\nTypeError: backup() takes exactly 5 arguments (2 given)\n", "type": "client_exception"}}