You can also try with utorrent? There should be some tutorials on the forums about how to portforward with utorrent and using no-ip duc.
Pretty much download Utorrent and go to options properties and set the port to 43594 (Default) and then make sure randomize ports is not checked and the other 3 are checked... Then make sure you no-ip duc has a IP like.... yourprivateserver.no-ip.org and then make sure all 3 of the options are green checked and then you are online