Swing/AWT/SWT :: Progress Bar Dialog Sometimes Doesn't Display Components

I wish to display a progress bar during a lengthy file translation process. When I created a ProgressBar class to do this and tested it with a short test program, it seemed to work fine. But when I add my ProgressBar class to a package containing various other classes, put that package in a jar file, and then execute the class using the progress bar from a menu in my main program, the frame of the progress bar shows up with the appropriate caption but the JLabel, JProgressBar, and JButton are not displayed. I have gone over my code numerous times and checked that the ProgressBar class constructor is getting the proper arguments.

// package gov.nasa.jpl.ephemeris;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* Progress bar with message text above the bar and a Cancel button below it
*/
public class ProgressBar extends JFrame {
private boolean _cancelled = false;
private JProgressBar _progressBar = null;

[Code] ....

I have also been wondering whether I need a separate instance of the border for each panel, or whether I can just create one instance and use it for all three panels.