Could it be that the extension does not work in case one uses MySQL prefixes?
In my error message, the following is stated:
SELECT distinct user.user_id,user.user_name,user.user_real_name FROM `mcswiki_revision`,`mcswiki_user` WHERE (user.user_id = revision.rev_user) AND (rev_page = 1) AND (rev_user > 0) AND (rev_deleted = 0) ORDER BY user.user_name ASC
but this should be
SELECT distinct user.user_id,user.user_name,user.user_real_name FROM `mcswiki_revision`,`mcswiki_user` WHERE (mcswiki_user.user_id = mcswiki_revision.rev_user) AND (rev_page = 1) AND (rev_user > 0) AND (rev_deleted = 0) ORDER BY mcswiki_user.user_name ASC
if I'm not mistaken? (But I don't know much about this.)
Cheers!