JPanel Problem with JInternaelFrame ?

[Jan Michael Soan]

Hello Everyone;
I have problem with viewing a JPanel with a JInternalFrame, my intention is to click a menuitem which is named item10, then view a JPanel object which should be displayed in a JInternalFrame but after trying the codes below I recieve a null pointer execption.
x's : I declared : static Login pass;
Problem Codes :
item10.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent h)
{
pass = new Login();
JInternalFrame f1 = new JInternalFrame("Login . . .", true,true,true,true);
f1.add(pass);
x1.add(f1);
}
});
Hope Someone would reply, thanks !