List category posts – Thumbnails are not displaying

we’ve been using List Category Posts to display different category posts on one page and it was working great until recently when the thumbnail images disappear. The ‘thumbnail=yes’ option is there. We can’t figure out how to get the thumbnail images to appear again. Any help is greatly appreciated.

Here’s the page: www.tomorrowsyouth.org/programs/international-internships/tyo-intern-alumni/

We’re using Version 0.22.3

Be sure you have post thumbnails implemented in the theme: http://codex.wordpress.org/Post_Thumbnails

Another way to more easily use thumbnails is via WordPress › Get the Image « WordPress Plugins