Network Latest Posts Shortcode not functional

I’ve just installed this plugin, and it’s activated on both sites in my network. However, when I click the shortcode button while on a page or post, all I get is a blank box with the title of the plugin at the top. There are no shortcodes displayed.

My site is at http://sensibility.com, and I want to add latest posts to the front page.

Any ideas for me? Deactivating other plugins made no difference.

Thanks,
Jennie