I’m having the same problem. The “Add New Page” button is grayed out, although I have permission to create a new page.
Edit:
Check your WordPress version. It turns out we are running version 3.4.2. The latest CMS Tree Page View requires WordPress 3.5.1.
Unfortunately, some WordPress themes can make finding the version difficult in both the frontend and the backend, so you may not catch this problem. To check your version, you can always look in “wp-includes/version.php”.
