[Theme: Twenty Eleven] Galleries don't display in carousel

I’m beginning to think this may be an issue of self-hosting a site with the Twenty Eleven versus one hosted on WordPress.com.

I can’t seem to get the same java script carousel effect for native galleries as shown in the See It In Action demo on WordPress.com. I can insert a gallery fine, with thumbnails, but clicking one will only open the image file or the page, not open the gallery with the carousel effect.

Anyone know if the java gallery is a custom implementation of the theme that only works on WordPress.com?

Here’s a link to the demo gallery:

http://twentyelevendemo.wordpress.com/2011/05/04/gallery-post/