Remote Desktop over VPN RAS

i setup RAS on 2 servers with NLB. from outside our network i can connect
with VPN. the virtual connection receives an IP from the range configured on
the RAS server (witch is a range from the internal IP networkspace).
Now i can ping servers inside the network from the vpn-client and dns-name
resolution seems to work too (ping myserver.mydomain.com resolves the ip and
receives repons from the server).
but i cannot connect with netbios (\\myserver.mydomain.com\c$) nor (and that
the important part) can i connect with remote desktop to machines in the
corp-network.
any hints where i could start troublshooting?
thanks a lot in advance, mike