I can't make Redhat 6.1 detect my printer (epson stylos color 640), but the
redhat 5.2 and 6.0 does it, and without a problem.
It's a bug in the installer - it forgets to add the line
alias parport_lowlevel parport_pc
Add the line manually and it will work.
Alternatively, get the 6.2 beta.