I get same error with 1.1.5

Unless anything here is wrong

$userid=$post[userid];

if ($userid!=0) {
$userinfo=$post;
// User Online Icon Hack by Chris Boulton
$status = $DB_site->query_first("SELECT session.userid,user.username,user.receivepm FROM session, user WHERE session.userid=user.userid AND session.userid='".intval($userinfo[userid])."'");
if ($status) {
$usersstatus = "<img src=\"images/online.gif\" border=0 alt=\"$userinfo[username] is Online\">";
} else {
$usersstatus = "<img src=\"images/offline.gif\" border=0 alt=\"$userinfo[username] is Offline\">";
}
// User Online Icon Hack by Chris Boulton
$username=htmlspecialchars($userinfo[username]);
$searchuser=urlencode($userinfo[username]);
//star hack
if ($userinfo[usertitle]=="Administrator") {