Exit Android App with external *actionscript.as* files

Hi, i'm trying to make this code work with a application that got 99% of code driving by external actionscript.as files;

In another app without any external call i mean no actionscript.as files, the code work very fine.

My goal is to shutdown any activity of the app when the user receive a call or something like that;

Many thanks in advance and sorry my english

Scene 1, Layer 'Layer 1', Frame 1, Line 14

1046: Type was not found or was not a compile-time constant: KeyboardEvent.

function handleActivate(event:Event):void

{

    NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.KEEP_AWAKE;

}

function handleDeactivate(event:Event):void

{

    NativeApplication.nativeApplication.exit();

}

function handleKeys(event:KeyboardEvent):void        ----- Line 14 -----

{

    if (event.keyCode == Keyboard.BACK)

    {

        NativeApplication.nativeApplication.exit();

    }

}

if (Capabilities.cpuArchitecture == "ARM")

{

    NativeApplication.nativeApplication.addEventListener(Event.ACTIVATE, handleActivate, false, 0, true);

    NativeApplication.nativeApplication.addEventListener(Event.DEACTIVATE, handleDeactivate, false, 0, true);

    NativeApplication.nativeApplication.addEventListener(KeyboardEvent.KEY_DOWN, handleKeys, false, 0, true);

}