KV-WebME CMS FRONT-END SUBMENU ERROR

I started to create a CMS with a book called CMS Design Using PHP and jQuery by kae verens. Below is my scenario;
After I create the sub-menu in i click View page in admin panel it shows the page link and content corretly but when i go to front-end and place mouse on the Parent menu, then i click on sub-menu, it shows 404 error.
Please refer to the example below;
when i place mouse on the menu, then place mouse on sub-menu, it shows like this
http://domain.com/menu/sub-menu and show 404 page

NOTE: Am using the source code i got from Packt , the original files on which the book is based.

Is there anyone who has ever developed his cms using this book and failed into the situation am in and came up with solution? if so guys help a brother.

Your help will be highly appreciated.Thanks