OKI B2540 - still doesn't print?
Enabling the error log for cups might show something useful: Press Alt+F2 and type
gksudo gedit /etc/cups/cupsd.conf
Then find the line that saysLogLevel warn and change it to LogLevel debug. After rebooting, there should be a file called "error.log" in /var/log/cups/. Make note of its last line, then try to print something. Does something new appear in the log?