Exclude Thumbnail from Slideshow

Kind of new to NextGen Gallery, so be patient with my naiveté.

I’m working on a site and have added some galleries, using a single thumbnail to open them up. When you click on the gallery thumbnail, it displays the thumbnail first, then the rest of the images in the gallery. You can see it, here:

My Site

Is there a way for me to keep the thumbnail as is, but NOT show it in the slideshow popup, when clicked? I tried excluding it in the manage galleries screen, but that affects displaying the thumbnail on the page, so that won’t work.

Thanks in advance!

http://ww.wp.xz.cn/plugins/nextgen-gallery/