Adding MC to stage

How can I link to a movie in my libary to tell it to behave like a button.
This is what I have tried but it’s not working.

var selectedButtons:Array = loadButtons();

var itemX:Number = 100; // initial item x position
var itemY:Number = 100; // initial item y position

for each( var buttonName:String in selectedButtons )
{
    var item:DisplayObject = null;

    if( buttonName == "apple" )
    {
      item = new apple();

      apple.addEventListener(MouseEvent.CLICK, shirt);
    function shirt(e:MouseEvent):void {
    trace("Clicked");
}
    }
    else if( buttonName == "banana" )
    {
       item = new banana(); 
    }
    else if( buttonName == "cherry" )
    {
        item = new cherry(); 
    }
        else if( buttonName == "pineapple" )
    {
        item = new pineapple(); 
    }
        if( item != null )
    {
        addChild( item );
        item.x = itemX;
        item.y = itemY;

        itemX += item.width + 20; // 20 = space between items
    }


}

As you can see I am adding the Movies to my stage throught thier class name(apples etc). How come I can’t link to it? Is it because I need to be using an instance name? And if so I would I assign one?