Image uploading works, but doesn't display

After getting a report that Omeka was giving an error (permissions based) upon trying to upload an image, I went to fix it and got the web server as the group owner with permission to write to the files directory. Now the images upload but they display the “fallback” broken image instead of a thumbnail. Clicking on that broken image link takes you to the image page and a link to the image which appears just fine if you click on it. I’m guessing that there is something wrong with the thumbnail creation, but I’m not sure what it is, because I don’t get an error, just a broken image in place of the thumbnail I’d expect. Any ideas of what might have gone wrong? I have the images set to private for now at http://www.recollectionsks.org, but if necessary, I can make them public for a bit!
Thanks!!

It was the fact that the new server I moved the site to didn’t have Imagemagick. It does now, and everything works. Consider this one closed!