I have 2 servers on gametracker I try to add a third one and not working IP 64.31.39.122;2802

Hope you can help my players want it.

There are a number of possible reasons. The most common reason would be a firewall. Assuming 2802 is also the query port, you need to make sure this port is open in your firewall.

Even though you didn't specify which game this server runs, I'm guessing its something Arma or Dayz. In this case, you may need to review http://www.gametracker.com/forums/forum.php?site=1&thread=94907