Starcraft Map Editor: How come they dont get minerals when the game starts?

I made a map and i placed everything in its place, i havent touched triggers, and when i play the game Use Map settings, the enemy does not make its scvs or drones or probes mine the minerals?? y is that? they dont do anything at all. if i make it as melee they will but i want to start at a specific location always. How do i fix this?