[Zope] Retrieving zope management password.

Now I have updated data.fs file and old username and password for ZMI don't work. Username password provided by client also don't work. Are username passwords stored in inituser file in zope install directory or inside data.fs file. I think these are stored in data.fs file becuase I only replaced data.fs file in old installation. I have used zpasswd.py to create new user, following the procedure written in admin guide and zope book, but that new user is not allowed to login. Is there any other way to create new user? -- Sukhwinder Singh