2 things:
#1: In the 2nd trigger, under actions, you want the preserve trigger action at the bottom not the top.
#2: In the 3rd trigger, under conditions, you want it to be:
CurrentSide owns Exactly 0 Any Unit
NOT
Side1, Side2, Side3, Side4 owns Exactly 0 Any Unit
Other than those things, it looks like a great map to me!
