JAVA: Screenshot after JFrame change just black

I've written a program which makes a screenshot of JFrame by clicking on JMenuItem. If I only run the .java file in Eclipse, everything works and the screenshot shows the JFrame perfectly. But if I open the JFrame as a link from another JFrame, the screenshot is black instead of showing the JFrame. Here's my code:

JFrame1.java:

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;


public class JFrame1 extends JFrame {

    static JFrame1 frame1 = new JFrame1();

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
             try {
                 frame1.setVisible(true);

            } catch (Exception e) {
              e.printStackTrace();
            }

          }
        });   
      }

    public void CloseFrame(){
        super.dispose();
    }    

    public JFrame1() {
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(50, 50, 800, 740);

        JButton ok = new JButton("OK");
        getContentPane().add(ok);
        ok.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                CloseFrame();
                JFrame2 frame2 = new JFrame2();
                frame2.setVisible(true);
                }
        });    
    }
}

With a button (ok) I can go to JFrame2.java.

JFrame2.java:

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class JFrame2 extends JFrame {

    static JFrame2 frame2 = new JFrame2();

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
             try {
                 frame2.setVisible(true);

            } catch (Exception e) {
              e.printStackTrace();
            }

          }
        });   
      }

    private void createMenuBar() {

          JMenuBar menubar = new JMenuBar();

          JMenu file = new JMenu("File");

          JMenuItem screen = new JMenuItem("Screenshot");
              screen.addActionListener(new AbstractAction() {

                  @Override
                  public void actionPerformed (ActionEvent e)
                  {
                      Dimension size = frame2.getSize ();
                      BufferedImage img = new BufferedImage (size.width, size.height, BufferedImage.TYPE_3BYTE_BGR);
                      Graphics g = img.getGraphics ();
                      frame2.printAll (g);
                      g.dispose ();
                      try
                      {
                          ImageIO.write (img, "png", new File ("screenshot.png"));
                      }
                      catch (IOException ex)
                      {
                          ex.printStackTrace ();
                      }
                  }
              });

          file.add(screen);
          menubar.add(file);
          setJMenuBar(menubar);
      }

    public JFrame2() {
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(50, 50, 800, 740);

        createMenuBar();
    }

}

If I click now on "Screenshot", it is just black. And if I run only JFrame2.java without running JFrame1.java before, the real image is saved. Why does the screenshot is black after going from one JFrame1 to JFrame2?