Ahh Mp Problem

programming flash
1

well its not really a problem its just i dont no how to do it
how do we make it so if the MP for example reaches 0 u cant use the skill anymore.

i thought it would be something like

onClipEvent(load){
if(_root.mp2 <= 0;
_root.skill2 = false;

but oviously its not working, so what would it be