So a couple minutes ago I was playing some customs with my buddy and he wanted to show me an infection map for an infection game. Well when we loaded the game it turned out to be incompatible with the forge world map! D: Anyone care to elaborate? Maybe the map wasn't entirely complete?
Some objects are required on a map for its gametype to work. http://www.forgehub.com/forum/halo-reach-forge-discussion/105195-required-forge-objects-guide.html