Revisor requires some packages when composing media. However, these are not in Fedora 11. I'm speaking of anaconda-runtime, gail, synaptics, vnc-libs, vnc-server, pirut(listed twice), kernel-xen(listed twice) and almost all fonts. The solution would be to drop them, beginning in line 1298 from cfg.py.
I commented out these packages, and the composing is working fine until now, but I can't assure that there is no lost functionality and maybe you'll have to do some research about these packages and their equivalents in Fedora 11. You can find the patched source code here: http://julian.fedorapeople.org/patches/revisor/cfg.py
I run into these error when I run revisor with the arguments from ticket #361 Fedora 11 with revisor 2.1.6.
Composing doesn't work anymore when commenting these out. It fails on Building images: Building Installation Images: Building Installation Images: 0.0%Building Installation Images: Building Installation Images: 0.0% Got an error from /usr/lib/anaconda-runtime/buildinstall (return code 1)