Suse10 domain users not visible in Win2k

I have a SuSE v10.0 primary domain controller and several Windows 2000 clients. I am able to add the win2k client computers to the domain with no problem, but when I try to add the users (which are already added to Samba on the server) I get a message saying that user doesn’t exist. When I click “browse” to see a list of user accounts available only “root” and “nobody” with a white x in a red circle over it shows up. any ideas why my users aren’t showing up?? I am VERY new to Linux, so any help is appreciated.