[Koha] Admin patrons are denied access to admin interface

Hi all, I elevated the privileges of a normal use to admin ones and moreover I created another one granted her the same privileges. For some reasons they can access the normal interface but they are denied the admin one. For the moment the only user allowed to enter the web-admin interface is kohaadmin but I should use that only to create patrons, right? What and where can I look at to allow those two users to enter the webadmin interface? BTW Koha is suppposed to authenticate users against AD but afaik if it doesn't find them in AD it should look at the local DB, should'n it? Thanks, Alex