I want to perform a backup of the database from OpenERP 6.1.1 go to Manage Database from the webclient sign up screen, then go to Backup, perform, select the database, put the master password and get a 61MB, when I download the file is only 586k and I get the following error:

   {"message": "OpenERP WebClient Error", "code": 300, "data": {"debug": "Client Traceback (most recent call last):\n  File \"/usr/local/lib/python2.6/dist-packages/

How can I backup the database from 6.1.1 from the database manager?