[I’ll delete your guest post]
Well, I’ve got good news for you. The plugin is working perfectly, and was designed to not need you to do anything in the header (so undo the stuff I see you’ve tried already), it’s all automatically done for you.
The reason it’s not working for you is because you currently don’t appear to have your hyperlinks enclosing the images, you have the hyperlink in front of the img tags, but not surrounding it, you need to have it like this: <a><img></img>[/url]
Once you fix that, it should work, but you typically use slimbox to display larger versions of thumbnails/smaller pictures, yours appears set to show the same image, which defeats the purpose (but you’re free to do what you like).