I would repeat the tutorial over again.

Also check your end_game function in your _zombiemode.gsc

Wouldn't of been more easily if you actually follow the tutorial.
It not meant to be:

trig = GetEnt("end_game", "targetname");
trig thread end_game();

It meant to be this:
[code]end_trig = getentarray( "end_game","targetn...