Users permissions

[Chuc]

I set up a W2K domain, but I had this problem: I logon as a domain user on a workstation, right clic on a shared folder, clic on sharing, clic permissions, and I can't see users and groups of the domain, in the window I can read "The server is not operational", I can see only local uses and computers. AD is active, what am I missing?
Thank you for help.