Win2003 with RRAS and OpenVPN

Am trying to get OpenVPN 2.0 rc20 to work on a Microsoft Windows 2003 server. OpenVPN connect alright and the logs is all fine. But no traffic can be sent over this line. Is like a firewall is restricting the traffic.

On the server, RRAS is active. Trying to configure Windows Firewall and it says it’s not possible because NAT is active.

The server has one network card if I remember correctly. Network interface has an internal IP number given by a dlink router.

How should I start to troubleshoot this issue?