I would guess your port is open for it? Port 7777? If you have access, just port forwarding your router and using that instead of hamachi is a lot easier. You can also hide your server from the launcher so no one else can get your IP as well.
In C:\Program Files (x86)\Renegade X\UDKGame\Config\UDKRenegadeX.ini, set bListed to false. Your server will no longer appear on the launcher.