Rollover Trouble

Ok… so i have this game, and something is supposed to happen when you roll your mouse over the enemy dude. It’s not happening. Here’s the code, tell me what’s wrong with it. The enemy dude is supposed to move when the mouse is rolled over it, by the way.

This is the code in the enemy dude:

onClipEvent (load) {
	spinspeed;
	xspeed = 0;
	yspeed = 0;
	xthrust = 0;
	ythrust = 0;
	friction = 0.9;
	function setThrust(num, thrust) {
		if (thrust<0) {
			thrust -= num;
		}
		if (thrust>0 or thrust == 0) {
			thrust += num;
		}
	}
}
onClipEvent (enterFrame) {
	spinspeed = xspeed*2;
	xspeed += xthrust;
	xspeed *= friction;
	yspeed += ythrust;
	yspeed *= friction;
	this._rotation += spinspeed;
	this._x += xspeed;
	this._y += yspeed;
}
on (rollOver) {
	setThrust(1, ythrust);
	setThrust(4, xthrust);
}
on (rollOut) {
	setThrust(0);
}

Update: I found out the problem, but I don’t know how to fix it. There is something wrong with the setThrust() function. I tried just saying xthrust = 4 and it worked. Please help!