Installed the plugin fine. It gives the 'crop' link next to the images. It loads the crop popup. However, when I click save it pauses for a second and then behind the popup I can see that it has reloaded the gallery page (above the previous gallery page) but highlighted in a red box. I assume this is because it cannot generate a error message so just reloads the page in the error box.
Basically, the image isn't cropped.