What did you use for the URI???
From the INSTALL file:
CUPS USB NOTES
--------------
If you are using the USB port, then the URI should be:
usb:/dev/usb/lp0
usb:/dev/usb/lp1
OR
usb://Samsung/CLP-310%20Series
usb://Samsung/CLP-310%20Series
usb://HP/Color%20LaserJet%20CP1215
usb://HP/Color%20LaserJet%202600n
usb://HP/LaserJet%201000
usb://HP/LaserJet%201005
usb://HP/LaserJet%201018
usb://HP/LaserJet%201020
usb://HP/LaserJet%20P1005
usb://HP/LaserJet%20P1006
usb://HP/LaserJet%20P1505
Don't use hp://<whatever> because that is for hplib (a closed source,
proprietary driver).