I have used this plugin successfully on a few sites, and I really love it. However, I can't get it to work on the site I'm working on now. When I click on "Thumbnail", the dialog box opens where I can choose which thumbnails to edit, but the area on the left where I'm supposed to be able to crop the image is empty - there's no image to crop!
There's a screenshot here:
Any suggestions? It might be a conflict with another plugin, but I disabled all the plugins I'm comfortable disabling, and that didn't help.