Java SE (Java Platform, Standard Edition)

Hi,

I have a doubt about the Java 3D programming. I have the following code:

import com.sun.j3d.utils.geometry.Box;
import com.sun.j3d.utils.universe.SimpleUniverse;
import java.awt.BorderLayout;
import java.awt.GraphicsConfiguration;
import javax.media.j3d.AmbientLight;
import javax.media.j3d.Appearance;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.ColoringAttributes;
import javax.media.j3d.DirectionalLight;
import javax.media.j3d.Material;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import javax.swing.JFrame;
import javax.vecmath.Color3f;
import javax.vecmath.Point3d;
import javax.vecmath.Vector3d;
import javax.vecmath.Vector3f;

public class Helicoptero extends JFrame
{
    /** Creates a new instance of Helicoptero */
    public Helicoptero() 
    {
        Canvas3D canvas3D = createCanvas3D();
        add("Center", canvas3D);
        BranchGroup scene = createSceneGraph();
        connect(canvas3D, scene);
    }

    private Canvas3D createCanvas3D() 
    {
        setSize(300, 300);
        getContentPane().setLayout(new BorderLayout());
        GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();
        Canvas3D canvas3D = new Canvas3D(config);
        setSize(300, 300);
        getContentPane().add(canvas3D);
        
        return canvas3D;
    }

    private BranchGroup createSceneGraph() 
    {
        BranchGroup objRoot = new BranchGroup();
        Box base = new Box();
        objRoot.addChild(base);
        objRoot.compile();
        
        return objRoot;
    }

    private void connect(Canvas3D canvas3D, BranchGroup scene) 
    {
        SimpleUniverse simpleU = new SimpleUniverse(canvas3D);
        simpleU.getViewingPlatform().setNominalViewingTransform();
        simpleU.addBranchGraph(scene);
    }
    
    public static void main(String[] args) 
    {
        new Helicoptero().setVisible(true);
    }
}

When I execute my program, appears a Window but with the background black, without the box that I had included on my application. Someone can help me and say me why the box not appears in that Window? What is the problem in my code?

Thanks.