SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.1.3): Invalid SQL: SELECT l.*, c.*, u.userid, u.username FROM lp1_links l, lp1_cats c LEFT JOIN bb2_users u ON u.userid = l.userid WHERE l.cat_id=c.cat_id AND l.link_id='26'
mysql error: Unknown column 'l.userid' in 'on clause'
mysql error number: 1054
mysql version: 5.0.51a-24+lenny2+spu1
php version: 5.2.6-1+lenny4
Date: 09.09.2010 @ 20:34
Script: /linklist.php?link=26
Referer: