Thats a common problem running on IIS
The link its posting to is: http://robert.aitchison.org/tiki-read_article.php/articleId=23&comzone=show after the .php the / should be a ? . also IIS is not secure with the default TikiWiki installs, so make sure you apply your own IIS security rules to the folders. IIS doesnt use .htaccess you'll need to convert those into IIS speak.
Hope it helps