MY DRAG & DROP JIGSAW STILL NOT WORKING!

Question

After 3 drag and drops of the puzzle i get this error:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at MultimediaProducttest_fla::MainTimeline/dropIt()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at MultimediaProducttest_fla::MainTimeline/pickUp()
ACTION SCRIPT 3!!! HELP PLEASEEEEEE!
restbar_btn4.addEventListener(MouseEvent.CLICK, restbar4Clicked);
museum_btn4.addEventListener(MouseEvent.CLICK, museum4Clicked);
sark_btn4.addEventListener(MouseEvent.CLICK,sark4Clicked);
market_btn4.addEventListener(MouseEvent.CLICK, market4Clicked);
park_btn4.addEventListener(MouseEvent.CLICK, park4Clicked);
function home4Clicked(event:MouseEvent):void {
    gotoAndPlay("Home");
    removeF();
function removeF():void {
    pone_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    pone_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    ptwo_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    ptwo_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    pthree_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    pthree_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    pfour_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    pfour_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    pfive_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    pfive_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    psix_mc.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
    psix_mc.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
    removeChild(pone_mc);
    removeChild(ptwo_mc);
    removeChild(pthree_mc);
    removeChild(pfour_mc);
    removeChild(pfive_mc);
    removeChild(psix_mc);
    pone_mc=null;
    ptwo_mc=null;
    pthree_mc=null;
    pfour_mc=null;
    pfive_mc=null;
    psix_mc=null;
function restbar4Clicked(event:MouseEvent):void {
    gotoAndPlay("Restaurant");
    removeF()
function museum4Clicked(event:MouseEvent):void {
    gotoAndPlay("Museum");
    removeF();
function market4Clicked(event:MouseEvent):void {
    gotoAndPlay("Market");
    removeF();
function park4Clicked(event:MouseEvent):void {
    gotoAndPlay("Park");
    removeF();
function sark4Clicked(event:MouseEvent):void {
    gotoAndPlay("Cutty");
    removeF();
var startX:Number;
var startY:Number;
var counter:Number=0;
pone_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
pone_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
ptwo_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
ptwo_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
pthree_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
pthree_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
pfour_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
pfour_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
pfive_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
pfive_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
psix_mc.addEventListener(MouseEvent.MOUSE_DOWN, pickUp);
psix_mc.addEventListener(MouseEvent.MOUSE_UP, dropIt);
function pickUp(event:MouseEvent):void {
    event.target.startDrag(true);
    feedback_txt.text="";
    event.target.parent.addChild(event.target);
    startX=event.target.x;
    startY=event.target.y;
function dropIt(event:MouseEvent):void {
    event.target.stopDrag();
    var myTargetName:String="target"+event.target.name;
    var myTarget:DisplayObject=getChildByName(myTargetName);
    if (event.target.dropTarget!=null&&event.target.dropTarget.parent==myTar get) {
        feedback_txt.text="Good Job!";
        event.target.removeEventListener(MouseEvent.MOUSE_DOWN, pickUp);
        event.target.removeEventListener(MouseEvent.MOUSE_UP, dropIt);
        event.target.buttonMode=false;
        event.target.x=myTarget.x;
        event.target.y=myTarget.y;
        counter++;
    } else {
        feedback_txt.text="Try Again!";
        event.target.x=startX;
        event.target.y=startY;
    if (counter==6) {
        feedback_txt.text="Congratulations, you've finished!";
pone_mc.buttonMode=true;
ptwo_mc.buttonMode=true;
pthree_mc.buttonMode=true;
pfour_mc.buttonMode=true;
pfive_mc.buttonMode=true;
psix_mc.buttonMode=true;

Answer 1

The 1009 error indicates that one of the objects being targeted by your code is out of scope.  This could mean that the object....
- is not in the display list
- doesn't have an instance name (or the instance name is mispelled)
- does not exist in the frame where that code is trying to talk to it
- is animated into place but is not assigned instance names in every keyframe for it
- is one of two or more consecutive keyframes of the same objects with no name assigned in the preceding frame(s).
If you go into your Publish Settings Flash section and select the option to Permit debugging, your error message should have a line number following the frame number which will help you isolate which object is involved.