Accelerometer function issue

Hi guys,

I'm very new to flash and AS3 and I'm getting an annoying issue. I'm currently trying to make a simple game using accelerometer controls, and it works fine for the first level, but as soon as it tries to jump to either another scene or frame 2 (I've tried having the different levels on either scenes or frames, and the error occurs regardless) I'm getting this error: TypeError: Error #1009: Cannot access a property or method of a null object reference.

From looking around on the web I can see that it's trying to load something that's not there, but I'm not sure at what point it's stopped existing. Do I need to terminate the function at the end of the 1st scene and then re-initialize?

Here is the first frame's code, the error message is: "TypeError: Error #1009: Cannot access a property or method of a null object reference. at ball_game_fla::MainTimeline/onAccUpdate()[ball_game_fla.MainTimeline::frame1:17]"

import flash.sensors.Accelerometer;import flash.events.AccelerometerEvent;
import flash.utils.Timer;
import flash.events.TimerEvent;
import flash.events.Event;


var isFalling:Boolean = false;
var theAcc: Accelerometer = new Accelerometer();
  theAcc.setRequestedUpdateInterval(10);
  theAcc.addEventListener(AccelerometerEvent.UPDATE,onAccUpdate);
stop();


function onAccUpdate(e:AccelerometerEvent)
  {
  ball.x -= (e.accelerationX * 10);
  ball.y += (e.accelerationY * 10);
  dummyBall.x = ball.x;
  dummyBall.y = ball.y;
  ballShadow.x = ball.x + 5;
  ballShadow.y = ball.y + 5;
   
  if (ball.x < 0){
  ball.x = 0;
   
  }else if (ball.x > stage.stageWidth){
  ball.x = stage.stageWidth;
  }
  if (ball.y < 0){
  ball.y = 0;
   
  }else if (ball.y > stage.stageHeight){
  ball.y = stage.stageHeight;
  }
   


  if(dummyBall.hitTestPoint ( hole.x, hole.y, true ) && isFalling == false){
  isFalling = true;
  hole.gotoAndPlay(2);
  ball.visible = false;
  ballShadow.visible = false;
  dispatchEvent(new Event("finished", true));
   
  }
}

Any pointers would be really useful