Is this user in the active directory or in a custom directory? I mean, if you create a text object with
Does that user appear? The license must be assigned to the user in the form DOMAINNAME\USERNAME as this user is displayed when it logs in to the AccessPoint (upper right corner, Logged In As: ...). Apart from that, the user needs permissions on the file. Make sure the user can open the folder without problems.
Hope that helps.