Facebook plugin produces errors

The Ultimate Facebook plugin produces the following errors:

[03-Jan-2012 14:07:02] PHP Fatal error: Call to undefined function add_action() in /home2/edberryc/public_html/wp-content/plugins/wpmu-dev-facebook/lib/wdfb_utilities.php on line 150

[03-Jan-2012 14:26:19] PHP Fatal error: Class 'WP_Widget' not found in /home2/edberryc/public_html/wp-content/plugins/wpmu-dev-facebook/lib/class_wdfb_widget_albums.php on line 5

[03-Jan-2012 14:29:26] PHP Fatal error: Class 'WP_Widget' not found in /home2/edberryc/public_html/wp-content/plugins/wpmu-dev-facebook/lib/class_wdfb_widget_likebox.php on line 6 /home2/edberryc/public_html/wp-content/plugins/wpmu-dev-facebook/error_log:

[03-Jan-2012 13:15:33] PHP Fatal error: Call to undefined function add_action() in /home2/edberryc/public_html/wp-content/plugins/wpmu-dev-facebook/wpmu-dev-facebook.php on line 32