I have an Epson Stylus Color 640 printer, connected via USB. The printer was originally a parallel printer, however the USB connection was made possible by a USB kit which Epson offered at one time. I do not know if they still offer this kit, but I have seen generic, similar kits at computer shows.

Most of the items under Printer Tools (clean heads, printhead alignment, etc.) work fine, however the selection for Ink Level does not. When it was connected via the parallel port (must be logged in as root for the Ink Level selection to work), it displayed the percentage of each color ink remaining, but under USB it displays an error indicating it must be a RAW printer. As a result, I depend on the lights on the printer itself to indicate when the black or color cartridge requires replacement.

Is this error coming up simply because it is now connected via USB?