Mover clip con Teclas con Flash

onClipEvent (load) {
speed = 20;
display = "press arrows";
}
onClipEvent (keyDown) {
if (Key.getCode() == 39) {
_x = _x+speed;
} else if (Key.getCode() == 38) {
_y = _y-speed;
} else if (Key.getCode() == 37) {
_x = _x-speed;
} else if (Key.getCode() == 40) {
_y = _y+speed;
}
display = Key.getCode();
}