So it seems this map (kismet perhaps?) has an issue with Marco's Rpg Mutator. When the wave ends, the map acts as if the game has ended, which would seem to be your purpose. However, after the trader round/ game end sequence effect and the next wave begins, my team and I were not able to spawn, nor were there any zombies spawning.
I will attempt this without the mutator and see how it plays.
A suggestion that I and my fellow squad has is for you to possibly make the trader as a destructible actor as opposed to being just a "one touch beacon". While the one touch does make for a much more strategic gameplay, I feel that it would be more fair for the player and overall a better experience if the trader had something like a door's welding integrity, for example, that way the zombies would need to "destroy" the trader, which would lead to the end of the match.