Nex Gen Gallery

Hi, I have nex gen set to default to thumbnails. When I click on one of the images it just opens in a new window, not to a slideshow. And when I click on the show slideshow button I get, sorry no page found. I feel like I am missing something fundamental. Any ideas.

http://216.104.175.116/current-exhibits-2/