Drag and Drop Multiple items to One Target

Thanks for the correction. I guess I'm even more of a beginner than I thought. If you have a moment to look at what I have done so far, I'd really appreciate it. Can the z-index of the dropped movie clip be changed or does it need to move completely off the target?

Thanks as well for any input you can provide!

var counter:Number = 0;
var startX:Number;
var startY:Number;

aAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
aAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
bAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
bAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
eAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
eAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
gAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
gAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
nAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
nAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
rAG_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
rAG_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);

function pickUp(event:MouseEvent):void {
    event.target.startDrag(true);
    reply_txt.text = "";
    event.target.parent.addChild(event.target);
    startX = event.target.x;
    startY = event.target.y;
}
function dropIt(event:MouseEvent):void {
    event.target.stopDrag();
    var targetaAG_mc:String = "target" + event.target.name;
    var myTarget:DisplayObject = getChildByName(targetaAG_mc);
    if (event.target.dropTarget != null && event.target.dropTarget.parent == myTarget){
        reply_txt.text = "Correct";
        event.target.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
        event.target.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
        event.target.buttonMode = false;
        event.target.x = myTarget.x;
        event.target.y = myTarget.y;
        counter++;
    } else {
        reply_txt.text = "Try Again";
        event.target.x = startX;
        event.target.y = startY;
    }
    if(counter == 6){
        reply_txt.text = "You Win!";
    }
}

aAG_mc.buttonMode = true;
bAG_mc.buttonMode = true;
eAG_mc.buttonMode = true;
gAG_mc.buttonMode = true;
nAG_mc.buttonMode = true;
rAG_mc.buttonMode = true;