Add Innerframes To Desktop Panel In For Loop

import javax.swing.*;
public class LoopFrame extends JFrame {
public LoopFrame() {
super("My loop Frames");
JDesktopPane desktop = new JDesktopPane(); //a specialized layered pane
JInternalFrame innerframe = new JInternalFrame("My loop Windows");

[Code] .....

I want to add 5 internal frames to a desktop panel it compiles but i get this error

//***********************************************err or******************************
this shows in the cmd when i run the program

Exception in thread "main" 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 :483)
at java.awt.Container.add(Container.java:410)
at LoopFrame.<init>(LoopFrame.java:27)
at LoopFrame.main(LoopFrame.java:44)
Press any key to continue . . .

************************************************** ***************************************