Hi Danny,
In order to actually troubleshoot and see the error, you have to enable full debug in fop2, you can do that by editing
/etc/syconfig/fop2
and add to OPTIONS "-X 511 -l /tmp" (that means full debug level, and log into /tmp). The options line should look somthing like:
OPTIONS="-d -X 511 -l /tmp"
(do not remove any extra options you might have had there, like -i -c, etc).
Then restart fop2, you will have two files, output.log and error.log, let fop2 run until it stops, and then check the /tmp/error.log file for the relevant information.
However, my suggestion is for you to upgrade to 2.27, there are some fixes that might ease/help in your situation, and perhaps it will fix your issue releaving you from doing the debugging log.
http://download.fop2.com/fop2-2.27-centos-i386.tgz
Best regards,