can't create BufferedImage

I am trying to create a BifferedImage and Graphics2D associated with a
JPanel. I understand that the JPanel must be displayable else the
createImage method may return null. However in my stub program below I
always get null returned from createGraphics. I obviously am missing
something but I can't figure out what. If the program below is run
without a runline parameter it does not attempt to create a
BufferedImage and it runs OK. If it is run with a runline parameter it
throws an exception because bh is null. Why?

Jay

public class Test extends javax.swing.JFrame {

    private static String[] opt = null;

    public Test() {
       init();
    }

    void init() {
       javax.swing.JPanel jContentPane = new javax.swing.JPanel();
       setContentPane(jContentPane);
       setSize(450, 350);
       javax.swing.JPanel graphPanel = new javax.swing.JPanel();
       java.awt.Dimension s = new java.awt.Dimension(400, 300);
       graphPanel.setPreferredSize(s);
       getContentPane().add(graphPanel, null);
       graphPanel.addNotify();
       s = graphPanel.getPreferredSize();
       System.err.println("Is JPanel=" +
          (graphPanel instanceof javax.swing.JPanel) +
          " " + s.width + "x" + s.height + " Displayable=" +
          graphPanel.isDisplayable() + " Headless= " +
          java.awt.GraphicsEnvironment.isHeadless());
       if(opt!=null && opt.length>0) {
          java.awt.image.BufferedImage bh =
             (java.awt.image.BufferedImage)graphPanel.createImage(
             s.width, s.height);
          java.awt.Graphics2D bufh = bh.createGraphics();
       }
    }

    public static final void main(String[] argv) {
       opt = argv;
       Test test = new Test();
       test.setVisible(true);
    }
}