Button issue

hello,

I'am new in as3 programming,

I use this code and there is nothing displayed on the screen.

package

{

import flash.display.Sprite;

import flash.display.Graphics;

import flash.events.Event;

import fl.core.UIComponent;

import fl.controls.Button;

public class Main extends Sprite

{

public function Main():void

{

init();

}

private function init ():void

{

var myButton:Button = new Button();

myButton.emphasized = false;

myButton.width = 150;

myButton.move(20, 20);

addChild(myButton);

}

}

}

Help me please.