For vBulletin 3.7 you need to edit the "save reports to database" plugin. The following code should work:
Code:
global $vbulletin;
$vbulletin->db->query("
INSERT INTO " . TABLE_PREFIX . "postreport
(postid, userid, reporttext, status, dateline)
VALUES
(" . $iteminfo['postid'] . ",
" . $vbulletin->userinfo['userid'] . ",
'". addslashes(htmlspecialchars_uni($vbulletin->GPC['reason'])) . "',
0,
" . TIMENOW . ")
");
Don't know if it the best solution.