This is because the website doesn't have an index page. Recently developers and
site owner don't store their index page as "index.html" or "index.php"
anymore, thereby preventing webspiders from cloning their site source codes.
Though, there's a way such site can be cloned. If you would like to clone ,
kindly drop the link to the site for cloning. I'm not showing us how it's
done, because developers spend their time, energy and resources in creating
those codes. You can simply appreciate them by buying their templates.