Class 'Zend_Exception' not found

I’ve just copied the latest Piwik folder to a new ‘analytics’ folder in my webserver hosted by IIS on Windows 2008 Server. I tried going to http://www.mydomain.com/analytics/piwik/index.php to start the installation after creating a MySQL database and user, where I was told I needed to execute some ‘cacls’ commands. I started with the first ‘tmp’ directory it requested, then refreshed the index.php page and have been given this error:

Fatal error: Class ‘Zend_Exception’ not found in C:\inetpub\wwwroot\analytics\piwik\libs\Zend\Exception.php on line 39

I cannot seem to continue with the installation since I continually get this error when trying to go to this page.

Help??

probably calcs commands that Piwik gives are maybe wrong. Sorry none of team members use IIS, but its important for us to make it work for IIS. So if you know how to change the calcs command to make it work let us know