Connection between clients and Windows 2000 server

I am having a problem to get access from client pc’s (Windows 98, Windows 2000 and Windows XP) to Windows 2000 server. This only happend if I am in the different segment with the server segment. For example when I am trying to get connection from windows xp client pc to windows 2000 server, i can see the server name but if I am 2x click it, nothing appear in the next window. I am already upgrade to win xp sp2. It is also happend if I am using windows 2000 pro and windows 98 to find the server, nothing appear. Please help.

Thank you.