(Help) Database Error

[gbml4u]

I got this problem on my site and i dont know how to fix it...if anybody knows how to fix them pls needing ur helps..

Invalid SQL:

		SELECT
			user.username, (user.options & 512) AS invisible, user.usergroupid,
			session.userid, session.inforum, session.lastactivity,
			IF(displaygroupid=0, user.usergroupid, displaygroupid) AS 
displaygroupid, infractiongroupid
		FROM session AS session
		LEFT JOIN user AS user ON(user.userid = session.userid)
		WHERE session.lastactivity > 1169626756
		ORDER BY username ASC;

MySQL Error  : Unknown column 'user.username' in 'field list'
Error Number : 1054

thanks in advanced