focussing swing buttons using tab key

I want to get focus on my swing buttons immediately when i open the page without the help of mouse for the first time.my code is working. but sometimes it is not working.here is my code.please reply what is the fault there?

code:

public class AstMonitor extends JApplet implementsActionListener,FocusListener,Runnable {

boolean keepTrying = true;
Thread astThread;

JButton sale = new JButton("12 Sale ");
public void init() {

resize(150,475);

setForeground( java.awt.Color.black );

setBackground( new java.awt.Color(237,237,237) );

setFont( new Font("Tacoma", Font.PLAIN, 12) );

GridLayout gl;
getContentPane().setLayout(new GridLayout(10,3));
nosale.setActionCommand("nosale");

nosale.addActionListener(this);

this.getContentPane().add(nosale);

nosale.setMnemonic('e');

nosale.setBackground(Color.pink);
astThread = new Thread(this);

astThread.start();

}
public void focusGained(FocusEvent fe)
{
if(fe.getSource()==nosale)

System.out.println(nosale.getLabel()+"gained");
if(fe.isTemporary())

System.out.println("Temporary Focus");

}
public void focusLost(FocusEvent fe)

{
if(fe.getSource()==nosale)

System.out.println(nosale.getLabel()+"lost");
}

Thanks.

Any idea about the above code.pls reply.anyone help me