Switching between jTabbedPane within a jTabbedPane

Question

I am creating an Applet on which has multiple tabs, but I have hit a wall. I know that Applet.setSelectedIndex(1); will change tabs between Lesson 1 & Lesson 2 and so on but is there a way I can change tabs between Lesson 1.1-1.5 with a button as Applet.setSelectedIndex(TAB NUMBER); doesn't work?

EDIT: SOLVED WITH THIS:

 private void Lesson11To12MouseClicked(java.awt.event.MouseEvent evt) {                                          
        Applet.setSelectedIndex(/*Whatever index*/);
        Lesson2TabbedPane.setSelectedIndex(/*Whatever index*/);
    }  

Thank you in advance :) Image Link: https://i.stack.imgur.com/z9QWZ.png

Mark Lang.