In the book it give me this piece of code:

package
{
 
  import away3d.containers.View3D;
  import away3d.lights.PointLight3D;
  import away3d.materials.BitmapMaterial;
  import away3d.materials.WhiteShadingBitmapMaterial
  import away3d.primitives.Cube;
  import away3d.primitives.Sphere;

  import flash.display.BitmapData;
  import flash.display.Sprite;
  import flash.events.Event;

public class MyFirstApp extends Sprite
{
 
  private var view : View3D;
  private var sphere : Sphere;


  public function MyFirstApp()
  {
  view = new View3D();
  view.x = 200;
  view.y = 200;
  addChild(view);
 
addEventListener(Event.ENTER_FRAME, onEnterFrame);

  var bmp : BitmapData = new BitmapData(200,200);
  bmp.perlinNoise(200, 200, 2, Math.random(), true, true);

var mat : BitmapMaterial = new BitmapMaterial(bmp);
 
  var cube : Cube = new Cube();
  cube.material = mat;
  view.scene.addChild(cube);

var sphere : Sphere = new Sphere();
view.camera.z = -50;
  sphere.segmentsW = 32;
  sphere.segmentsH = 32;
  sphere.material = new WhiteShadingBitmapMaterial(bmp);
  sphere.x = 200;
  view.scene.addChild(sphere);


  var light : PointLight3D = new PointLight3D();
      light.y = 500;
      view.scene.addLight(light);
   
  }

    private function onEnterFrame(ev:Event):void
    {
   
  sphere.rotationY += 2;
  view.render();

 
}
  }
}

BUT FOR MY SURPRISE..THE SPHERE DOESNT MOVE OR ROTATE AND A OUTPUTE APEAR SAYING ME:

TypeError: Error #1009: No se puede acceder a una propiedad o a un método de una referencia a un objeto nulo.
at MyFirstApp/onEnterFrame()
TypeError: Error #1009: No se puede acceder a una propiedad o a un método de una referencia a un objeto nulo.
at MyFirstApp/onEnterFrame()

Where is the probleme???