Simple If Statement movement

programming flash
1

So I have been on hiatus from coding flash for like a year or more. Trying to remember just simple stuff is hard.

What am I doing wrong here. This is linking to a movieClip.

onClipEvent(load){
	_root._x=200;
	this._x=0;
	this._y=200;
	speed=3;
}
onClipEvent(enterFrame){
	this._x-=speed;
	if(this._x>0){
		this._x+=speed;
	}

}