queryfejl ved opgradering fra MySQL 4.x til 5.0

SELECT online.user_id, user.name, user.sex, user.pic, user.zip, user.area, user_fav.fav, DATE_FORMAT(FROM_DAYS(TO_DAYS(NOW())-TO_DAYS(user.birth)), '%Y')+0 AS age, user_attrib.att_admin
        FROM ($DB.online online, $DB.user user
            LEFT JOIN $DB.user_fav user_fav ON '$USERID'=user_fav.user_id && online.user_id=user_fav.fav)
        LEFT JOIN $DB.user_attrib ON user.id=user_attrib.user_id
        WHERE online.user_id=user.id
        ORDER BY $order user.name

jeg får nu pludselig denne fejl:
Unknown column 'online.user_id' in 'on clause'