Display most active users

[qpurser]

I tried to add this but got an error.
Any help why this is happening?
Thanks

Database error in vBulletin 4.1.5:

Invalid SQL:
select count(postid) as count, post.userid, user.username from V4post INNER JOIN V4user on user.userid = post.userid where post.dateline > 1311952983 GROUP BY post.userid ORDER BY count DESC LIMIT 1;

MySQL Error : Unknown column 'post.userid' in 'field list'
Error Number : 1054
Request Date : Friday, August 5th 2011 @ 11:23:03 AM
Error Date : Friday, August 5th 2011 @ 11:23:04 AM
Script : http://xxx.com/V4/forum.php
Referrer : http://xxx.com/V4/forum.php
IP Address :
Username :
Classname :
MySQL Version : 5.0.91-log