Multihomed Nic and Port Forwarding RRAS

I have a server that has an external NIC with 4 static ip addresses attached to it and one nic with an internal address. Using RRAS, I would like to forward port 5500 to an internal ip address. Normally, this would work by simply setting it up in the services/ports tab of the nic's properties in RRAS mmc, which I have done. The interface is supposed to forward 5500, on the wan interface, to port 5500 of the internal computer's ip address...

But it isn't working. netstat -na doesn't show that 5500 is listening, on any address and inbound connections fail, obviously. What do I need to do to resolve this?