Function question

Hi

I just learnt how to write a function, and it is so difficult [I do enjoy however though]
Anyway,
I’m planning to make a button that when clicked, it will rotate 4 same movie clips.
This is my code:

var rotateDirection;
function rotateStart (rotateSpeed, gearSet) {

for (i=1; i<3; i++) {
this[gearSet+i]._rotation+= (rotateSpeed*rotateDirection);
}
}
this.onEnterFrame=function () {

a_btn.onRelease=function () {
var rotateDirection = 1;
rotateStart (10, “a_gears”);
rotateStart (10, “b_gears”);

}

}

please let me know where it goes wrong?
thank alot [you never know how much I appreciate this]