>I have quite a interesting problem. And I don't think it's >freeRADIUS-related
You are correct. It's an AD problem. Something is wrong with the schema for those imported accounts. SAM-Account-Name should be of the type ADSTYPE_OCTET_STRING (case insensitive unicode string). Ivan Kalik Kalik Informatika ISP - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
