... You have to enable them stupid
I smell ban.
On topic: if you are indeed talking about Rotondo's zombie mod, there here's what you do to make it work.
1. Start a mini-game.
2. In the Zombie Options menu, make sure that the Enable Zombies options is enabled (make sure the box next to it is checked).
3. In the mini-game options menu, make sure the playertype you're using is the Survivor playertype. The zombies will only chase and attack that playertype.
4. Enjoy your mini-game.
