[JAVA]Problema con JDialog

[tcc]

Salve di nuovo.Ho un'altro problema devo inserire due JPanel in un JDialog.
Questo è il mio codice:

 
public class FormCorpusTIMIT extends JDialog {

   
  public FormCorpusTIMIT() {
   
  }

    public void show(IGraphicInterface igi) {
        this.setTitle("Form corpus");
        this.setBounds(500,250,500,200);
        this.setLayout(new BorderLayout());
        this.getContentPane().add(BorderLayout.CENTER,new PanelCentralCorpusTIMIT());
        this.getContentPane().add(BorderLayout.SOUTH,new PanelButtonCorpusTIMIT());

        this.setVisible(true);
        
    }



  }

dove 


public class PanelCentralCorpusTIMIT extends JPanel{
    
    private JTextField directory;
    private JTextField annotation;
    private JTextField istant;
    
    public void PanelCentralCorpusTIMIT(){
        this.setLayout(new GridLayout(3,2));
        this.add(new JLabel("directory"));
        this.add(this.directory = new JTextField(15));
        this.add(this.annotation = new JTextField(15));
        this.add(this.istant = new JTextField(15));
    }
    
    
}

e

public class PanelButtonCorpusTIMIT extends JPanel{
    
    private JButton buttonCreate;
    private JButton buttonClose;
    public PanelButtonCorpusTIMIT(){
        this.add(new JButton("Create"));
        this.add(new JButton("Close"));
    }
    

}

Adesso i bottoni si vedono ma JLabel e JTextField no.Dove è il problema?