Cannot access a property or method of a null object reference

1

So I have this target movieclip and some dragable square movieclips that are created every 5 seconds, and I’m trying to removechild them when they touch the target but as soon as they appear on stage I get this evil error, and when I drag them onto the target nothing happens!

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Function/<anonymous>()

I’ve googled over 9000 times trying to figure out what’s causing it but everything i try doesn’t work! Or it just gives me another error in place of it.

Anyway this is (most of) the code

function addTarget(event:Event):void
            {

                var newTarg:targ1 = new targ1();
                addChild(newTarg);
                newTarg.x = 69;
                newTarg.y = 175;

                removeEventListener(Event.ENTER_FRAME, addTarget);
            }
function AddBox(event:Event):void
            {
                //adds square to the stage
                var newBox:Box1 = new Box1();
                addChild(newBox);

                //adds drag and drop functions 
                newBox.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
                newBox.addEventListener(MouseEvent.MOUSE_UP, drop);

            //makes it a button 
                newBox.buttonMode = true;

                removeEventListener(Event.ENTER_FRAME, AddBox);

            }

           -This is the bit that causes the evil-
            function BoxRemove(e:Event):void
            {
                    if (newBox.hitTestObject(newTarg))
                    {
                        removeChild(newBox);
                        trace("yay");
                    }
             }

                addEventListener(Event.ENTER_FRAME, BoxRemove);

Thanks for the help :egg: