Error #1009 Cannot access a property or method of a null object reference...help?

Hi there,

Im having the dreaded Error #1009 and its taken me all day to figure it out and yet I have no idea what is causing this!!

Im on Flash CS4 using AS3.

Error says : “TypeError: Error #1009: Cannot access a property or method of a null object reference. at oranges_proto4_fla::who_mc_105/frame101()”

Basically its a movie clip inside another movie clip and I’m trying to have a tooltip info box on mouse over hover on an object AFTER the movie clip is playing. But every single time I get this message and its stopping me from progessing my project…

Here’s the code:

import fl.transitions.Tween;
import fl.transitions.easing.*;

overlogo_mc.visible=false;

function worker1Over(event:MouseEvent):void{

overlogo_mc.visible=true;
overlogo_mc.gotoAndPlay(2);
//function that reports mouse coordinates
function reportstageMouse(event:MouseEvent):void{
    
    
    var myStageX:Number=Math.round(event.stageX);
    var myStageY:Number=Math.round(event.stageY);
    
    var xTween:Tween=new Tween(overlogo_mc,"x",Strong.easeOut,overlogo_mc.x  , myStageX, 1, true);
    var yTween:Tween=new Tween(overlogo_mc,"y",Strong.easeOut,overlogo_mc.y  , myStageY, 1, true);
    
    
    
}
stage.addEventListener(MouseEvent.MOUSE_MOVE, reportstageMouse);

}

function worker1Out (event:MouseEvent):void{
overlogo_mc.visible=false;

}

function worker1Click (event:MouseEvent):void{
// Do whatever crap you want on click of logo!
}

worker1a_mc.addEventListener(MouseEvent.ROLL_OVER, worker1Over);
worker1a_mc.addEventListener(MouseEvent.ROLL_OUT,w orker1Out);
worker1a_mc.addEventListener(MouseEvent.CLICK,work er1Click);

stop();

Help?