Exhibit Thumbnails

I have installed the latest version of Exhibit and followed the instructions. I did not change anything on the Config file as it all seemed fine, and I set up my images directory.

The problem I am having is that my THumbnails are not appearing as previews in the admin panel or when I publish the site. The file name appears but no graphical representation?

MAybe I have not set the correct CHMOD settings or other part of Config file?