Access variable in parent from loaded SWF

programming flash
1

Hey people,

I have a mystery error going on when I try and access a variable in my main movie from a loaded SWF. As far as I can tell from most feedback I’ve gotten I should be able to do it with
MovieClip(parent.parent).varName. I’m simply trying to set a boolean to true to indicate that a button has been clicked. When the button is clicked I get the error - Error #1009: Cannot access a property or method of a null object reference.

What am I doing wrong?

Here’s the code:

function but_1_down(event:MouseEvent):void{
workChoice = 1;
var nextF_AplhaTween_1:Tween = new Tween(nextFrameButt, “alpha”, Regular.easeIn, 1, 0, 1, true);
gotoAndStop(2);
MovieClip(parent.parent).thumbClicked = true;

}