attachment_fu not resizing in production

I've been having a lot of problems getting attachment_fu properly set up, both on my local Mac and my production server. I finally got ImageMagick installed and working with JPEG on my production server. Unfortunately, it's still not resizing when run through mod_rails. If I start up a mongrel server on the production server in either the production or development environment pictures are resized just fine.

So, ImageMagick is confirmed to be working correctly (at least that headache is over), and everything works fine when running a single mongrel instance, but it doesn't work in the "live" environment using mod_rails.