Try the following, it's how I quickly and easily made one :
First, be sure to have your firewall turned off.
Then, click on Start > Run. In the window which appear, type cmd.exe
In this black console, type ipconfig and press Enter.
Note somewhere, on a paper, the IP adress which is displayed in "IP Adress".
Then, use the default gateway adress (usually 192.168.1.1) to connect to your router, and go where you can actually write the informations about your port.
For the "descrption", I advise you to use a simple description without points or space (like, "SRB2"). Inbound and private ports, keep 5029. Set type to UDP, and for the private IP adress, complete the two last numbers that you saw on the console earlier. Don't forget to enable it~
If it's still doesn't work, it's possible that the antivirus is the cause, but I'm not sure about that.
EDIT : Heh, Aries, simultaneous reinforcements~