Remote Desktop Error connecting

Hi i’ve this problem with Remote Desktop.

Situation:
buildup a VPN connection between two locations over the internet.
on location 1 there’s a terminal server and i want to connect workstations from location 2 using remote desktop.

Problem:
On LOC-1 every workstation can connect to the terminal server.
On LOC-2 no one can connect, except my own laptop.

pinging is successful from both side.

workstations are running XP SP Pro.

Can anyone give some tips?

Thanx