arrow keys right and left in different scenes

Hi

i have different scenes once clicked it goes to next
similarly want to have right and left keys want to work with
but its only working in the 1st Scene, once user clicks and goes to next
scene then arrow keys stop working,

can anyone tell me how key can work in all scenes

Actionscript Code:

import flash.system.fscommand;
import flash.ui.Keyboard;
import flash.events.Event;
import flash.events.KeyboardEvent;


btn_next.addEventListener(MouseEvent.CLICK,next_Slide);
btn_prev.addEventListener(MouseEvent.CLICK,prev_Slide);
btn_exit.addEventListener(MouseEvent.MOUSE_DOWN, closeApp);

stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);


btn_no1.addEventListener(MouseEvent.CLICK,setContent);
btn_no2.addEventListener(MouseEvent.CLICK,setContent);
btn_no3.addEventListener(MouseEvent.CLICK,setContent);
btn_no4.addEventListener(MouseEvent.CLICK,setContent);
btn_no5.addEventListener(MouseEvent.CLICK,setContent);
btn_no6.addEventListener(MouseEvent.CLICK,setContent);
btn_no7.addEventListener(MouseEvent.CLICK,setContent);
btn_no8.addEventListener(MouseEvent.CLICK,setContent);
btn_no9.addEventListener(MouseEvent.CLICK,setContent);
btn_no10.addEventListener(MouseEvent.CLICK,setContent);
btn_no11.addEventListener(MouseEvent.CLICK,setContent);
btn_no12.addEventListener(MouseEvent.CLICK,setContent);



function closeApp(event:MouseEvent):void
{
    fscommand("quit");
}

function next_Slide(event:MouseEvent):void
{
    prevScene();
}

function prev_Slide(event:MouseEvent):void
{
    nextScene();
}

function keyDownHandler(event : KeyboardEvent):void
{
/*  if (event.keyCode == Keyboard.RIGHT)
    {

        nextScene();
    }

    if (event.keyCode == Keyboard.LEFT)
    {

        prevScene();
    }*/
}




function setContent(event:MouseEvent):void
{

    switch (event.target.name)
    {

        case "btn_no1" :
            gotoAndPlay("1","Scene 1");
            break;

        case "btn_no2" :
            gotoAndPlay("1","Scene 2");
            break;

        case "btn_no3" :
            gotoAndPlay("1","Scene 3");
            break;

        case "btn_no4" :
            gotoAndPlay("1","Scene 4");
            break;

        case "btn_no5" :
            gotoAndPlay("1","Scene 5");
            break;

        case "btn_no6" :
            gotoAndPlay("1","Scene 6");
            break;

        case "btn_no7" :
            gotoAndPlay("1","Scene 7");
            break;

        case "btn_no8" :
            gotoAndPlay("1","Scene 8");
            break;

        case "btn_no9" :
            gotoAndPlay("1","Scene 9");
            break;

        case "btn_no10" :
            gotoAndPlay("1","Scene 10");
            break;

        case "btn_no11" :
            gotoAndPlay("1","Scene 11");
            break;

        case "btn_no12" :
            gotoAndPlay("1","Scene 12");
            break;

        case "btn_reply" :
            gotoAndPlay("1","Scene 1");
            break;
    }




}