Network Connection

I have 3 Servers in building A and 1 Server in building B. The Server in building B is connected to the Servers in building A through a T1 line. The Servers and the workstations (Clients) are able to see each other until I added another Server to Building A. All the servers can see the new servers likewise the new Server can communicate with the other servers and workstations with the exception of the WORKSTATIONS in building B. I cannot map drives from any of those PC to the new Server.
I have checked the DNS and WIN address of the Server they attached to and the new Server and everything seems to be fine. Moreover, the Server the said WORKSTATIONS are attached to was able map drive to other Servers. What could be the problem? Help!!!