Java SE (Java Platform, Standard Edition)

Hello,
I try to modify an Java3D example,
I want to display a 3D-Text,
but the setString(String s) of the Text3D-class causes this execption,
if String s is not null:

***** polygon with only one vertex?! *****

java.lang.IllegalArgumentException: TriangleArray: illegal vertexCount
at javax.media.j3d.TriangleArray.<init>(TriangleArray.java:119)
at com.sun.j3d.utils.geometry.GeometryInfo.getGeometryArray(GeometryInfo.java:2557)
at javax.media.j3d.Font3D.triangulateGlyphs(Font3D.java:402)
at javax.media.j3d.Text3DRetained.updateCharacterData(Text3DRetained.java:684)
at javax.media.j3d.Text3DRetained.setString(Text3DRetained.java:234)
at javax.media.j3d.Text3D.setString(Text3D.java:350)
at Static3DWorld.createSceneGraph(Static3DWorld.java:138)
at Static3DWorld.<init>(Static3DWorld.java:44)
at Static3DWorld.main(Static3DWorld.java:185)

Here is the source-code:

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GraphicsConfiguration;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.media.j3d.Appearance;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.ColoringAttributes;
import javax.media.j3d.Font3D;
import javax.media.j3d.FontExtrusion;
import javax.media.j3d.Material;
import javax.media.j3d.Shape3D;
import javax.media.j3d.Text3D;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import javax.swing.JFrame;
import javax.vecmath.Color3f;

import com.sun.j3d.utils.universe.SimpleUniverse;
public class Static3DWorld extends JFrame {
private Transform3D rotate1 = new Transform3D();
private Transform3D rotate2 = new Transform3D();

/**
* There are three fundamental
* steps in creating a 3D world:
* Create a Canvas3D object.
* Create a scene graph.
* Connect the Canvas3D object to a BranchGroup object
* that points to the root of the scene graph.
*
*/
public Static3DWorld()
{
super("Static3DWorld");

//Create a Canvas 3D Object
Canvas3D canvas3D = createCanvas3D();

//Create a BranchGroup Object,
//that points to the root of the scene graph
BranchGroup scene = createSceneGraph();

//Connect them
connect(canvas3D, scene);


this.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
this.repaint();
}

/**
* The createCanvas3D() method adjusts
* the size of a JFrame.
* The method then creates a canvas3D object
* and adds it to the center of the JFrame.
* The Java 3D API specific task is to call
* the static method getPreferredConfiguration(),
* and pass the result into the Canvas3D constructor.
* @return the Canvas3D Object
*/
private Canvas3D createCanvas3D()
{
//JFrame size
setSize(300, 300);


//Set BorderLayout
getContentPane().setLayout(new BorderLayout());

//Java3D-Specific Task
GraphicsConfiguration config =
SimpleUniverse.getPreferredConfiguration();

//Create the Canvas3D Object and pass the
//configuration to the Construktor
Canvas3D canvas3D = new Canvas3D(config);

//add the Canvas to the JFrame
getContentPane().add(canvas3D);

//return it
return canvas3D;
}

/**
* The createSceneGraph() method.
* The BranchGroup object, objRoot,
* points to the root of the scene graph.
* The rotator object is a TransformGroup
* that rotates an object Pi/4 over the x axis
* and Pi/4 over the y axis.
* This TransformGroup is added
* as a child of the objRoot.
* @return
*/
private BranchGroup createSceneGraph()
{

//create the BranchGroup (root of the scenegraph)
BranchGroup objRoot = new BranchGroup();

//create a TransformGroup
TransformGroup rotator = new TransformGroup(
rotateCube());
//add it to the root of the scene Graph
objRoot.addChild(rotator);

//create a new Shape3D-Object
Shape3D s3d = new Shape3D();

//create a Font
Font f = new
Font("SansSerif",32,Font.PLAIN);


//create a 3D-Font
Font3D f3d = new Font3D(f,new FontExtrusion());

//create a 3DText
Text3D txt = new Text3D();
txt.setFont3D(f3d);

/*
* The line, that causes the
* java.lang.IllegalArgumentException.
* txt.setString(null) will not throw it.
*/
txt.setString("Test");
//End of the problem-line

txt.setCapability(Text3D.ALLOW_STRING_WRITE);

//add the Text3D-Object to the Shape3D Object
s3d.setGeometry(txt);

//create a new Appearance-Object
Appearance a = new Appearance();
Material m = new Material();
m.setLightingEnable(true);
ColoringAttributes y =
new ColoringAttributes(new Color3f(1.0f,1.0f,0.0f),ColoringAttributes.FASTEST);
a.setColoringAttributes(y);
a.setMaterial(m);

//add it to the Shape3D-Object
s3d.setAppearance(a);

//Part of the original Example
//add a ColorCube
//rotator.addChild(new ColorCube(0.3));

//add the Shape3D-Object to the TransformGroup-Object
rotator.addChild(s3d);

//compile the BranchGroup
objRoot.compile();

return objRoot;
}

private Transform3D rotateCube()
{
rotate1.rotX(Math.PI / 4.0d);
rotate2.rotY(Math.PI / 4.0d);
rotate1.mul(rotate2);
return rotate1;
}
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 Static3DWorld().setVisible(true);
}
}

It must be a stupid mistake,
because it?s my first experience with java3D.
Thanx for reading and thinking!