Index: includes/class-wp-comments-list-table.php                                                                                                                                                                                            
===================================================================
--- includes/class-wp-comments-list-table.php   (revision 17348)
+++ includes/class-wp-comments-list-table.php   (working copy)
@@ -41,13 +41,14 @@
        }    
 
        function prepare_items() {
-               global $post_id, $comment_status, $search;
+               global $post_id, $comment_status, $search, $comment_type;
 
                $comment_status = isset( $_REQUEST['comment_status'] ) ? $_REQUEST['comment_status'] : 'all';
                if ( !in_array( $comment_status, array( 'all', 'moderated', 'approved', 'spam', 'trash' ) ) )
                        $comment_status = 'all';