DK Remote Administrator connection via VPN

Hi, I'm running DX Remote Administrator v6.3 on a Win7 local machine and try to register DX services running on a different network.  I've made a VPN connection to the remote network and can ping the remote server hosting the DX services, but it seems that DX Administrator only scans my local network and not the VPN.  Manual registration with the IP or FQ domain name also fails.

Any idea on how to get around this or whether it's possible to connect to DX services over a VPN?

Thanks

krugerga