Multiple roles through Active Directory

System

How should I define my Active Directory attribute to allow users to have multiple roles (i.e. admin and author). I've tried creating the bm-tsRoles attribute and comma-delimit the entries-- that didn't work. I also tried creating the attribute as a multiple-values attribute and that doesn't work either. If I have one value in the attribute set to author, TS recognizes the user as author. But as soon as I set another attribute, say admin, TS no longer recognizes the user as either admin or author. Any ideas?