Unread posts in my groups

user warning: Unknown column 'node_comment_statistics.last_comment_timestamp' in 'field list' query: SELECT node.nid AS nid, node.type AS node_type, node.title AS node_title, users.name AS users_name, users.uid AS users_uid, og_ancestry.nid AS og_ancestry_nid, node_comment_statistics.last_comment_timestamp AS unknown FROM node node LEFT JOIN og_ancestry og_ancestry ON node.nid = og_ancestry.nid INNER JOIN node node_og_ancestry ON og_ancestry.group_nid = node_og_ancestry.nid LEFT JOIN og_uid node_og_ancestry__og_uid ON node_og_ancestry.nid = node_og_ancestry__og_uid.nid INNER JOIN users users ON node.uid = users.uid INNER JOIN node_access na ON na.nid = node.nid WHERE (na.grant_view >= 1 AND ((na.gid = 0 AND na.realm = 'all') OR (na.gid = 0 AND na.realm = 'og_public'))) AND ( (node.status <> 0) AND (node_og_ancestry__og_uid.uid = 0) )ORDER BY unknown DESC LIMIT 0, 25 in /home/excessvb/public_html/sites/all/modules/views/includes/view.inc on line 765.