TypeError: Error #1009: Cannot access a property or method of a null object reference. at ColoringScreen/freezeColor() - actionscript-3

Question

hi I am once again asking for pointers on what I did wrong here the code works fine but when I test to play it the output message has this:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at ColoringScreen/freezeColor()
here's the code
public class ColoringScreen extends MovieClip {
var bitmapDt:BitmapData = new BitmapData (176.8, 176.8);
var ct:ColorTransform = new ColorTransform();
var hexaColor:*;
var myObject:Object;
public function ColoringScreen() {
// constructor code
chBackBtn.addEventListener(MouseEvent.CLICK, backtoMainScreen)
bitmapDt.draw(ColorPickerMc.spectrum);
ColorPickerMc.spectrum.addEventListener(MouseEvent.CLICK, freezeColor);
addEvents(oneMc, twoMc, threeMc, fourMc, fiveMc, sixMc, sevenMc, eightMc, nineMc, tenMc, elevenMc, twelveMc, thirteenMc, fourteenMc, fifteenMc, sixteenMc, seventeenMc, eighteenMc, ninteenMc, twentyMc, twentyoneMc, twentytwoMc, twentythreeMc, twentyfourMc, twentyfiveMc);
}
private function addEvents(...objects){
for(var i:Number=0; i<objects.lenght; i++){
objects[i].addEventListener(MouseEvent.CLICK, selectObject);
}
}
private function selectObject(e:MouseEvent){
myObject = e.target;
ColorPickerMc.spectrum.addEventListener(MouseEvent.MOUSE_MOVE, updateColor);
}
private function backtoMainScreen(e:MouseEvent) {
MovieClip(stage.getChildAt(0)).gotoAndStop("Intro");
}
private function updateColor(e:MouseEvent){
hexaColor = "0x"+bitmapDt.getPixel(ColorPickerMc.spectrum.mouseX, ColorPickerMc.spectrum.mouseY).toString(16);
ct.color = hexaColor;
myObject.transform.colorTransform = ct;
}
private function freezeColor(e:MouseEvent){
myObject.transform.colorTransform = ct;
ColorPickerMc.spectrum.removeEventListener(MouseEvent.MOUSE_MOVE, updateColor);
}
}
I know it's been asked a million times but I'm still scratching my head as to what property or method or what instance am I lacking cuz I checked it and all seem to be in place I named my instances and movie clip symbols all of it are in the same keyframe why does my freezeColor not work anymore? any help would be much appreciated