src\starling\textures\ConcreteRectangleTexture.as, Line 49 1046: Type was not found or was not a compile-time constant: RectangleTexture.

Starling framework showing this error in flash professional cs6

i was trying to run the simple starling code . My path was ok.

package

{

import flash.display.Sprite;

import starling.core.Starling;

[SWF(width="400", height="300", frameRate="60", backgroundColor="#ffffff")]

public class Game extends Sprite

{

    private var _starling:Starling;

    public function Startup()

    {

        _starling = new Starling(Game, stage);

        _starling.start();

    }

}

}