Actually, i figured it out. Lines 651 to 663, that sql statement is missing TABLE_PREFIX, so it can't find the tables ^^. Should look like this.
Code:
// SELECT SQL for signups for this event
$signups = $db->query_read("
SELECT ea.userid, ea.response, ea.signupname, ea.comment, ea.signup_date,
arm.m_name,arm.m_class,arm.m_race,arm.m_level,arm.ai_name,arm.ai_class,arm.ai_race,arm.ai_level,arm.aii_name,arm.aii_class,arm.aii_race,arm.aii_level,
userfield.$field5, userfield.$field9
FROM ".TABLE_PREFIX."wowraid ea
LEFT JOIN ".TABLE_PREFIX."userfield AS userfield ON userfield.userid = ea.userid
LEFT JOIN ".TABLE_PREFIX."armorydata arm ON arm.userid = ea.userid
WHERE eventid = 0".$eventinfo['eventid']."
AND ocdate = '".$signupdate."'
ORDER BY
ea.response, ".$orderby."
");