Thread: JInternalFrame isnt working why

Hello,

I'm trying to write a JFrame with a JInternalFrame. I have JMenuBar and JMenuItem when I click it,it should open new JInternalFrame.

The problem is when I use JDesktopPane it overwrites my mainFraim.getContentPane(). And when I try to add JDesktopPane into
mainFraim.getContentPane().add(JDesktopPane) it doesnt work can you pls help me to find why? or try to figure out how to add it into my mainFrame.

desk = new JDesktopPane();
frmTitsFireCrisis.getContentPane().add(desk,BorderLayout.CENTER);
 
JMenuItem Sim = new JMenuItem("Simlation of the crisis");
	//	Sim.setAction(action);
		Sim.setMnemonic('S');
		Sim.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,0));
 
		Sim.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
			JInternalFrame iT = new JInternalFrame("Crisis");	
			iT.setVisible(true);
			iT.setResizable(true);
		    iT.setClosable(true);
		    iT.setMaximizable(true);
		    iT.setIconifiable(true);
		    iT.setBounds(200,200,200,200);
 
		    //frmTitsFireCrisis.getContentPane().add(iT);
//			iT.getContentPane().add(new JButton("but"));
			desk.add(iT);
			try{
				iT.setSelected(true);
			}
			catch (Exception ex){
				ex.printStackTrace();
			}
			}
		});