A possible problem is:
The printer device name is set to /dev/usb... in TurboPrint Setup / xtpsetup.
With CUPS 1.2.x or higher this is no longer possible.
Use the symbolic name "usb://manufacturer/model" instead (e.g. "usb://canon/ip2000" - use the drop down list in xtpsetup next to the field "device name").