How do I drag and drop multiple objects in a mask?

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I’ve been working on a flash simulator to show what our night vision product would look like in the dark. I have been successful in making it work with the following code below. Yet I cannot add a “reticle” image (or symbol) to the draggable mask to make it work. Can someone help me with the code? I looked for hours on the internet and I cannot get it to work. I am new to Flash but am starting to learn as much as I can.[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]Actionscript 3 Code:[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]img_nv.mask = mask_mc;[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]mask_mc.buttonMode = true;[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]mask_mc.addEventListener(MouseEvent.MOUSE_DOWN, dF);[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]stage.addEventListener(MouseEvent.MOUSE_UP, dropF);[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]function dF(event:MouseEvent):void{[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] mask_mc.startDrag();[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]}[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]function dropF(event:MouseEvent):void{[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] mask_mc.stopDrag();[/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean] [/FONT][/COLOR]
[COLOR=#333333][FONT=adobe-clean]}

image_nv is the background and mask_mc is the circle.[/FONT][/COLOR]