It's difficult to diagnose the issue without seeing your code, but here are a few general suggestions:
Check that you have properly set up your menu items with the appropriate event listeners. Make sure that you are using the correct event listener for the action you want to take when the menu item is clicked (e.g. ActionListener for responding to clicks).
Double-check that the code to display the new window is actually being executed when the menu item is clicked. You can add a print statement or breakpoint to check if the code is being reached.
Make sure that your new window is properly constructed and visible. Check that you have properly set the layout and added any necessary components.
If you are still having issues, try simplifying your code to isolate the problem. You can also try searching for similar examples online or consulting Java documentation for guidance.