Hittest, collision detection?

1

I don’t really understand this, when searching for it I’ve found several different ways, but all of them using some kind of hitTest. example:


if (this, hitTest(_root.object)) {
//my code
}

but this doesn’t work for my very beautiful game, here is the code:


onClipEvent(enterFrame) {
_x -= speedx;
_y += speedy;

if (this, hitTest(_root.stjarna)) {
this._x += 20;
}

if (Key.isDown(Key.UP)) {
//_rotation -= 2;
this._y -= 20;
	}
	
if (Key.isDown(Key.DOWN)) {
//_rotation += 2;
this._y += 20;
	}

if(_y>480){
_y = 480;	
}

if(_y<-20){
_y = -20;	
}


}

and here is the game: http://erikhk.mine.nu/dump/files/rymdskeppv4.swf
the spaceship is named skepp, and the stars is named stjarna…
what am I doing wrong?? I’ve tried at least 4 methods, none of them working (for me)…