Multiple Domains

We are running two domains, Our server is on XYZ domain and most of the users are on ABC domain. When users on XYZ domain access they see their files with out a problem, however when users from ABC domain access they get: "The user with the username 'ABC\drew' could not be found." is this a trust issue or will it simply not work accross domains? Thought I should check before I spend too much time trying to figure it out.

Thanks
Drew

Please name FileVista users exactly as the qualified domain user name, ie.  create a FileVista user named exactly "ABC\drew".