In trying your online demo, the Add Categories function does not work.

It looks to be corrected in your demo now, however on my download the add category button still is not working.

Please download the latest version from our site to fix the problem:
http://www.viart.com/downloads/viart_shop-5.zip

thank you, I will do that.
But to streamline things, is there just a particular page I can replace?

Still waiting on a reply back...

You need to update two files:
admin/admin_items_list.php
templates/admin/admin_items_list.html

Thank you Vito!