Ultra newbie question regarding Movieclips as buttons

programming flash
1

this is a really really basic problem im having…

i created the following code:

function onClick(evt:MouseEvent):void
{
    this.gotoAndPlay(2);
}

block1_mc.buttonMode = true;
block2_mc.buttonMode = true;
block2_mc.buttonMode = true;

block1_mc.addEventListener(MouseEvent.CLICK, onClick);
block2_mc.addEventListener(MouseEvent.CLICK, onClick);
block3_mc.addEventListener(MouseEvent.CLICK, onClick)

However, im not getting any animation after I click on the buttons… why is that?

Thanks in advance!