Make sure that you purchased and installed Layered Popups for WordPress version 4.60 or higher. Login Box add-on helps you to add login form to any popup. The workflow is the same as for subscription form – just insert appropriate shortcodes into layer content. After that you can use popup as a login form. Login Box is a perfect way to extend functionality of your website.
Demo: http://codecanyon.net/item/login-box-layered-popups-addon/11179607