I followed the answer given to same question I'm asking, but get stuck at the point shown below.
Answer I used came from here: How do I get my Canon MX420 printer working?
Point where I ran into a problem:
aa@aa-laptop:~$ sudo /usr/sbin/lpadmin -p MX420USB -m canonmx420.ppd -v cnijusb:/dev/usb/lp0 -E
lpadmin: Unable to copy PPD file!
Thanks, Brian
