Hi there,
Something is causing a 500 Server Error on your blog, which is also the reason why WPP can't work properly.
Try any of the following:
- Edit your site's wp-config.php file and set
WP_DEBUG
to true:define('WP_DEBUG', true);
. That way, WordPress will output the error message on screen and you'll know exactly what's going on. - Ask your hosting to check the error logs for you, specifically those that might be related to admin-ajax.php.