Images not loading into dropdown

Hi, First I would like to thank you for your plugin. It is very easy to use and quite elegant. However, I am having an issue. I am working on the website http://www.KevinWilliamsArt.com. I added media to the library yet they do not show up in the dropdown. Images I added to the library before installing the plugin do show up as choices for the galleries, but anything I added after the plugin was already installed does not seem to show up in the list. Any help you can give? Thank you.

http://ww.wp.xz.cn/extend/plugins/tinymce-thumbnail-gallery/