[Plugin: Facebook Comments for WordPress] ERROR! Invalid application ID, Notification settings

I added the plugin for one of my client’s websites, on the front end the plugin works great, however, we don’t recieve e-mail or facebook notifications for new comments, and on facebook’s comment moderation tool, most of the comments are not displayed, I’d appreciatte any help with this matter, We’ve considered removing the plugin and using facebook’s development code directly however we don’t want to loose the comments already made in the site

http://wordpress.org/extend/plugins/facebook-comments-for-wordpress/