Mail Enabled Object cannot be found on GAL

Hey guys just curious if anyone of you had experience on Exchange 2003, mail enabled AD user objects cannot be found at all on GAL, but users can send email just fine, I'm currently trying to search for articles related to this, if you have an input thank you very much.

Just want to update I made sure "Hide from Exchange address lists" is unchecked, I also found out this article:

http://forums.msexchange.org/m_1800424713/mpage_1/key_/tm.htm#1800424763