Dissapearing menu bar

Hi,

I've cobbled together some code using NetBeans 6.1. A reduced version
of the code is below. When I run it, it sometimes shoes the menu bar
and sometimes doesn't. Any idea why? I'm also having some difficulty
with action listened, but I'll deal with that later.

Regards,
JNY

import java.lang.reflect.InvocationTargetException;
import javax.swing.*;
import java.awt.*;
import java.awt.GridLayout;
import javax.swing.JPanel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class Main extends JFrame{

    public static void main(String[] args)
    {

    final JFrame frmMainFrame = new JFrame("2D-CA Viewer-ImportData");
    frmMainFrame.setLayout(new GridLayout(5, 5));
    JPanel pnlCAPanel = new JPanel(new FlowLayout());
    frmMainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frmMainFrame.setSize(500, 500);
    frmMainFrame.setVisible(true);

    JMenuBar menuBar = new JMenuBar();
    JMenu file = new JMenu("File");
    menuBar.add(file);
    JMenuItem getData = new JMenuItem("Get Data");
    file.add(getData);
    frmMainFrame.add(menuBar);
    frmMainFrame.setJMenuBar(menuBar);

}

}