addChild problems with internal moviclips

I have a menu, and the menu has a few movie clips acting as my buttons. When I click on the button I want to bring what ever area of the site that button is linked to, to the front of the others that are on the stage.

I have my movie clips that are my sections to the website all on their own layers. Do they need to be on the same layer to be able to index their childIndex?

This is the code I have, but I can’t seem to get it working.

groupDiningBtn_mc.addEventListener(MouseEvent.CLICK, groupDining);

function groupDining(event:MouseEvent):void
this.setChildIndex(groupDiningBtn_mc(, (this.numChildren - 1));

I get this error:
1180: Call to a possibly undefined method groupDiningBtn_mc.