Domains and VPN and DSL

What I have is a NT wan and have 3 remote locations of one I can use Netork Neighborhood to browse and I can see all servers and workstation. But the other two I can, I can ping and use the run \\10.0.0.2 which points at one server and can logon to it. We are tcp/ip and have Wins and DNS setup on all servers. I have comapired all setting on all sights and they appear to be the same. Also I can’t seem to be able to get the trust relationsip resolved. I get the message that the PDC can’t be found, yet I can logon to anyone of them.
What piece of the puzzle am I missing

Thank you

Larry