LPRng is the default printing system in Red Hat 7.3 and (IIRC) 7.1 so I would think it's also the default printing system in 7.2.

Did you install the Red Hat CUPS rpms or did you install CUPS from source? Do you see anything in /var/log/cups/{access,error,page}_log?

If the job was cancelled it sounds like a permissions issue. Check the configuration files in /etc/cups. Did you log into the web interface as root? If this doesn't help try the http://www.cups.org/ newsgroups.