I need some triggering help plz

I need some triggering help plz

basically im trying to do an ammo trigger (no its not another zombie game something different ) i got most of it kinda worked out but having trouble with stopping the unit from attacking when ammo runs out, i tried eveything that i could think of (well what would be considered the most obvious) any one got any clues how to do it?

An Easy way to do this is:

Event:
Then You ammo equal to 0

Action:
Set Enemy to Ally

Nice one works a treat