Automatic Image Crop no longer working

I’ve been developing a site on another server and I recently moved it to an Amazon EC2 server.

But I’ve noticed that WordPress no longer crops my images when I add a feature, which is kind of important to my design.

I works on my old server. Even on my local machine. I’ve tried a clean install on the new server, but that doesn’t work either. Is there something in the php.ini that would effect this?