Canvas paint never gets called - Repaint and ServiceRepaints.

Question

I have a problem that My Canvas never gets Drawn or the Image never gets Displayed;
I am not sure if there is a DeadLock or If there is nothing to be painted,
but when I enable the Debugger I notice that it never enters the paint method. ( I call Repaint and ServiceRepaints)
If however I make the thread that calls setImage external to my Canvas Class the images do get Displayed.
   //Create the Canvas Class, Start Thread Display Canvas
   frame = new ImageCanvas();
    frame.addCommand(exitCommand);
    frame.addCommand(backCommand);
    frame.setCommandListener(this);
    frame.start();
    display.setCurrent(frame);
//Display Image
public class ImageCanvas extends Canvas implements Runnable {
protected void paint(Graphics g) {
  g.drawImage(offscreen, Constants.XPOS, Constants.YPOS,  Graphics.LEFT | Graphics.TOP);
  private void setImage(Image img, String title) {
    this.setTitle(title);
    offscreen = img;
    repaint();
    serviceRepaints();
public void run() {
     while(true){
       if (Constants.IMGLOCK != null) {
         synchronized (Constants.IMGLOCK) {
            setImage(Constants.IMAGE, title);
            Constants.IMGLOCK.setLockBoolValue(false);
             image_created = true;
      } else {
           Constants.IMGLOCK.wait(10);
}

Answer 1

I found the BUG, But do not understand Why this is Needed to add,
the Canvas every Time to the Display.
Can someone please Explain ???
private void setImage(Image img, String title) {
    this.setTitle(title);
    offscreen = img;
    repaint();
    display.setCurrent(this);  //<<<<<<WHY ????
    serviceRepaints();
  }