Error #1009

hey everyone,

i have something wierd…
de error #1009 cannot access a property or method of a null object reference.
but the code i use doesnt have anything that is null…

Mol.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
function mouseDownHandler(event:MouseEvent):void {

gotoAndStop(“Main”);

}

this is the code i have reapeten 5 times on multiply frames.
(i do have changed the names ect.)
the “Main” is a label on a frame.

when i click on 1 button, it works fine. when i click on the button that leads me back to “Main” it works, BUT then he gives the error and i cant do a thing anymore…

i hope someone knows an answer…

thanks…