404 error popularity contest

I love Alex Kings’ ‘popularity contest’; it seems to work on my blog (www.cidz.nl). However, one of his other plugins: 404 notifier gives the following error:

404 URL: http://www.cidz.nl/wp-content/plugins/popularity-contest.php?ak_action=css

Referred by: http://www.cidz.nl/wp-admin/post-new.php?posted=518

any idea what could be wrong?