AS3 Error When Trying To Remove a Movieclip from the Stage

Question

I have an actual movieclip on the main timeline called "img_mc" which I want to remove when a certain frame is hit. So I placed the following code on that frame: removeChild(img_mc) - even though Flash removes it, I get the following error:

 ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.
at flash.display::DisplayObjectContainer/removeChild()

I don't understand what I am missing here? I also tried

 this.removeChild(img_mc); and

 stage.removeChild(img_mc);

Thanks!

Answer 1

I created a function:

function stopTheScript() {
    if (img_mc.parent){
        img_mc.parent.removeChild(img_mc); 
    }
}

which seems to work- meaning I don't get an error - however I don't quite understand why? I thought any movieclip placed on the timeline is automatically a child?