problem on button

[udayforu_1986]

if i click majesty button
it should disply 4 more buttons
1)animations 2)visual effects 3)multimedia 4)server based

but not showing

my code is

import java.io.*;
import java.awt.*;
import java.awt.event.*;
class Demoframe extends Frame implements ActionListener
{
Button b1,b2,b3,b4,cb1,cb2,cb3,ad1,ad2,ad3,m1,m2,m3,m4;
Panel p,p2,p3,p4,p5,p6,p7,p8;
Demoframe(String title)
{
super(title);
p=new Panel();
p2=new Panel();
p3=new Panel();
p4=new Panel();
p5=new Panel();
p6=new Panel();
p7=new Panel();
p8=new Panel();
b1=new Button("Home");
b2=new Button("Courses");
b3=new Button("Exit");
b4=new Button("Login");
cb1=new Button("Majesty");
cb2=new Button("Excellency");
cb3=new Button("Merit");
ad1=new Button("councellor");
 ad2=new Button("accountant");
 ad3=new Button("Manager");
m2=new Button("Visula effects");
m3=new Button("Multi media");
 m1=new Button("Animations");

m4=new Button("Server based technology");

p.add(b1);
p.add(b2);
p.add(b3);
p.add(b4);


add(p,BorderLayout.NORTH);
b1.addActionListener(this);
b3.addActionListener(this);
b2.addActionListener(this);
b4.addActionListener(this);
setSize(400,400);
setVisible(true);
}
               public static void main(String args[])
                   {
                   new Demoframe("Hapl 1.0 v");
                    }

public void actionPerformed(ActionEvent e)
{


                 if(e.getSource()==b1)
                      {

                       setBackground(Color.white);

                        p3.removeAll();
                        p4.removeAll();
                               }

     

     if(e.getSource()==b2)
        {

          

        setBackground(Color.white);
       p4.removeAll();
          p3.add(cb1);
        p3.add(cb2);
        p3.add(cb3);     
  setVisible(true);
          add(p3,BorderLayout.SOUTH);
     cb1.addActionListener(this);
       cb2.addActionListener(this);
        cb3.addActionListener(this);
 if(e.getSource()==cb1)
{
p3.add(m1);
p3.add(m2);
p3.add(m3);
p3.add(m4);

  setVisible(true);
setBackground(Color.white);
m1.addActionListener(this);
       m2.addActionListener(this);
        m3.addActionListener(this);


 
          add(p3,BorderLayout.SOUTH);
        

  }
                                   
}

                                 if(e.getSource()==b3)
                                      {
                                     System.exit(0);
                                       }
                  

                   if(e.getSource()==b4)
                     {
                     setBackground(Color.white);
                     p4.add(ad1);
                      p4.add(ad2);
                     p4.add(ad3);
                      p3.removeAll();
                       setVisible(true);

                        add(p4,BorderLayout.WEST);
                      ad1.addActionListener(this);
                      ad2.addActionListener(this);
                     ad3.addActionListener(this);
                         



  }
}
}

[Norm]

After you change the contents of a container, you need to tell the container to redo the display of its contents. I think validate() does that.