c3700 can't add custom service for port forwarding

I just bought a C3700-100NAS to replace my comcast box, and I am trying to add a custom service for port forwarding so I can view my webcam outside of my network. I use dydns so I can access each one. Once I go to the add custom service, I add the service, IP, and ports, and then I click apply.

When I go back and look at the list, there is nothing there.

Help!