Games dropping off the tracker

Anyone know why games that are up don't show up on the tracker. At the moment the games display on winbolo.net shows 3 games, including the game on my server (optonline.net). The tracker in winbolo only shows one game. My game was idle for 15 or more minutes with no one joining, so this might cause it. Any way to keep the games on the game tracker?

Thanks.

If the tracker restarts it will take upto 5 minutes for all games to reappear on it.