Ошибка Java JInternalFrame при следующем показе

У меня проблема с отображением jInternalFrame из другого jInternalFrame в JDesktopane, я использую IDE Netbeans. Сначала не возникает никаких проблем, но когда jInternalFrame закрывается с помощью dispose() и вы хотите показать снова, появляется ошибка.

Это сообщение об ошибке:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: illegal component position
at java.awt.Container.addImpl(Container.java:1093)
at javax.swing.JLayeredPane.addImpl(JLayeredPane.java:230)
at javax.swing.JDesktopPane.addImpl(JDesktopPane.java:474)
at java.awt.Container.add(Container.java:410)
at InternalTes.FrameMaster.menuTambahActionPerformed(FrameMaster.java:83)
at InternalTes.FrameMaster.access$000(FrameMaster.java:13)
at InternalTes.FrameMaster$1.actionPerformed(FrameMaster.java:49)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

Это код FrameMaster (JInternalFrame):

package InternalTes;
/**
 *
 * @author Vikar
 */
public class FrameMaster extends javax.swing.JInternalFrame {

/**
 * Creates new form FrameMaster
 */
public FrameMaster() {
    initComponents();
}

private static FrameMaster instance;
public static FrameMaster getInstance() {
    if(instance == null){
        instance = new FrameMaster();
    }
    return instance;
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    btnShowChild = new javax.swing.JButton();

    btnShowChild.setText("Show");
    btnShowChild.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnShowChildActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(btnShowChild)
            .addContainerGap(336, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(238, 238, 238)
            .addComponent(btnShowChild)
            .addContainerGap(17, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

private void btnShowChildActionPerformed(java.awt.event.ActionEvent evt) {                                             
    // TODO add your handling code here:
    FrameChild wd = FrameChild.getInstance();
    if(wd.isVisible()){
       wd.toFront();
    }else {
        Window.jDesktopPane1.add(wd);
        wd.setVisible(true);
    }
}                                          

// Variables declaration - do not modify                     
private javax.swing.JButton btnShowChild;
// End of variables declaration                   
}

Это код FrameChild (JInternalFrame):

package InternalTes;
/**
 *
 * @author Vikar
 */
public class FrameChild extends javax.swing.JInternalFrame {

/**
 * Creates new form input
 */
public FrameChild() {
    initComponents();
}

private static FrameChild myInstance;
public static FrameChild getInstance() {
    if(myInstance == null){
        myInstance = new FrameChild();
    }
    return myInstance;
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    btnClose = new javax.swing.JButton();

    btnClose.setText("jButton1");
    btnClose.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnCloseActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(311, Short.MAX_VALUE)
            .addComponent(btnClose)
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(244, Short.MAX_VALUE)
            .addComponent(btnClose)
            .addContainerGap())
    );

    pack();
}// </editor-fold>                        

private void btnCloseActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    dispose();
}                                        


// Variables declaration - do not modify                     
private javax.swing.JButton btnClose;
// End of variables declaration                   
}

Для Window (JFrame) я не включил его сюда, потому что код внутри просто обычный JFrame и JDesktoPane. Пожалуйста, мастер программирования на Java, пожалуйста, поддержите, эта проблема сводит меня с ума уже полтора года. Мой проект системной информации застрял только из-за этой проблемы, у меня нет проблем с использованием неразветвленного JInternalFrame.