#1009: Cannot access a property or method of a null object reference

programming flash
1

Hi all

I have a preloader.swf which, in turn, loads a portfolio.swf.

The portfolio.swf runs fine, however, when I run the preloader, I get:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at portfolio()

This is an error in portfolio.as and the section of code giving the error is:

// Volume control
            var ratio_volume:Number;
            var trackBounds:Rectangle = track_mc.getBounds(track_mc);
            var xPos:Number = trackBounds.x;
            var yPos:Number = trackBounds.y;
            var widthPos:Number = trackBounds.width-track_mc.slider_mc.width;
            var heightPos:Number = 0;
            var bounds:Rectangle = new Rectangle(xPos,0,widthPos,heightPos);
            
            track_mc.slider_mc.x = widthPos;
            track_mc.mouseEnabled = false;
            track_mc.slider_mc.buttonMode = true;
            track_mc.slider_mc.addEventListener(MouseEvent.MOUSE_DOWN,dragSlider);
            stage.addEventListener(MouseEvent.MOUSE_UP,stopSlider);
            
            function dragSlider(event:MouseEvent):void 
            {
                event.target.startDrag(false,bounds);
                addEventListener(Event.ENTER_FRAME,setVolume);
                mutebutton_mc.gotoAndStop(1);
            }
            
            function stopSlider(event:MouseEvent):void 
            {
                track_mc.slider_mc.stopDrag();
                removeEventListener(Event.ENTER_FRAME, setVolume);
            }
            
            function setVolume(event:Event):void 
            {
                ratio_volume = track_mc.slider_mc.x/widthPos;
                soundVol.volume = ratio_volume;
                SoundMixer.soundTransform = soundVol;
            }