Trouble with keyboard events

1

Hello

Ive been working on creating a 3d earth using papervision, I got it working however I want to add the ability to zoom in and out using the + and - keys, however I cant seem to get it to work. below is what im using.

in the main function:


addEventListener( KeyboardEvent.KEY_DOWN, keyDownHandler );

the keyDownHandler function:


private function keyDownHandler( event:KeyboardEvent ):void
{
     switch (event.keyCode)
     {
          case 107:
               _camera.zoom += 10;
               break;
          case 109:
               _camera.zoom -= 10;
               break;
     }
}

any help would be awesome.