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.