HELP WITH AS3 Removing Movie Clip

well this is my code to bring it onto the stage

import flash.events.MouseEvent;

pills.addEventListener(MouseEvent.CLICK, arrest)

function arrest(pEvent:MouseEvent):void{

          if(pEvent.target==pills){

                    var carimage: policecar= new policecar();

                    carimage.x=0;

                    carimage.y=0;

                    this.addChild(carimage);

          }

}

and the remove is under a different clip

stop();

bars1.addEventListener(MouseEvent.ROLL_OVER, barsout)

function barsout(pEvent:MouseEvent):void{

          if(pEvent.target==bars1){

                    this.removeChild(carimage);

          }

}

even when i add the latter code into the origininal code above it tells me access of undefined property (carimage)