Not sure if this will help with your specific issue, but wanted to post this info for any other folks having issues with the plugin.
We are migrating a site from Blogger to WordPress. When we first activated the plugin, it didn't appear to be working either. After some research, we figured out it was because all the post images were hosted on third-party sites (e.g., Picasa). Once we moved all the images to the WordPress Media Library & updated the posts accordingly, the plugin worked great! It appears the plugin only works on images that are stored in the WordPress Media Library, fwiw.
Thanks to Samuel Aguilera for a terrific & very easy-to-use plugin!