Why not show out the bitmap material sphere?

package {
    import flash.display.Sprite;
 
    import org.papervision3d.cameras.Camera3D;
    import org.papervision3d.core.proto.MaterialObject3D;
    import org.papervision3d.materials.BitmapFileMaterial;
    import org.papervision3d.materials.WireframeMaterial;
    import org.papervision3d.objects.DisplayObject3D;
    import org.papervision3d.objects.Sphere;
    import org.papervision3d.scenes.MovieScene3D;
    import org.papervision3d.materials.ColorMaterial;
 
    public class Main extends Sprite
    {
        private var _container :Sprite;
        private var _scene :MovieScene3D;
        private var _camera :Camera3D;
 
        private var _material:MaterialObject3D;
        private var _displayObj:DisplayObject3D;
 
        public function Main()
        {
 
            _container = new Sprite();
            _container.x = 100;
            _container.y = 100;
 
 
            addChild( _container );
 
 
            _scene = new MovieScene3D( _container );
 
 
            _camera = new Camera3D();
            _camera.z = -500;
            _camera.zoom = 5;
 
            _material = new BitmapFileMaterial("texture.jpg");
 
            _displayObj = new Sphere(_material,  80, 10, 10);
 
            _scene.addChild(_displayObj);
 
            _scene.renderCamera(_camera);
        }
    }
}