I've been trying to install zencart without success.

I've already uploaded all the files twice (different ftp clients), have created the configure.php files, modified access to files and folders (chmod), and always get a 500 server error page when hiting the install page.

Checking the error.log in the store (catalog) directory, the following error shows up:
PHP Fatal error: Cannot instantiate non-existent class: notifier in /home/mydomain/public_html/store/includes/autoload_func.php on line 79


Does anyone know how to sort this problem?