Help fix my site!

Question

Im creating a site for hw in flash, I made a button but when I click it, it brings it up but it says TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at mywebsite_fla::MainTimeline/pOut()
what is wrong?
how do I fix this?

Answer 1

here is my coding
stop();
import flash.events.MouseEvent;
// home button definition \\
home_btn.addEventListener(MouseEvent.MOUSE_OVER, hOver);
home_btn.addEventListener(MouseEvent.MOUSE_OUT, hOut);
function hOver(event:MouseEvent):void{
    home_btn.alpha-= 0.4;
function hOut(event:MouseEvent):void{
    home_btn.alpha = 1;
// Portfolio button definition \\
Portfolio_btn.addEventListener(MouseEvent.MOUSE_OVER, pOver);
Portfolio_btn.addEventListener(MouseEvent.MOUSE_OUT, pOut);
Portfolio_btn.addEventListener(MouseEvent.CLICK, pClick);
function pClick(event:MouseEvent):void{
    gotoAndStop("getPortfolio");
function pOver(event:MouseEvent):void{
    Portfolio_btn.alpha-= 0.4;
function pOut(event:MouseEvent):void{
    Portfolio_btn.alpha = 1;
// Contact Me button defintion \\
Contact_btn.addEventListener(MouseEvent.MOUSE_OVER, cOver);
Contact_btn.addEventListener(MouseEvent.MOUSE_OUT, cOut);
function cOver(event:MouseEvent):void{
    Contact_btn.alpha-= 0.4;
function cOut(event:MouseEvent):void{
    Contact_btn.alpha = 1;
// Links button definition \\
Links_btn.addEventListener(MouseEvent.MOUSE_OVER, lOver);
Links_btn.addEventListener(MouseEvent.MOUSE_OUT, lOut);
function lOver(event:MouseEvent):void{
    Links_btn.alpha-= 0.4;
function lOut(event:MouseEvent):void{
    Links_btn.alpha = 1;