Hi all :))
The problem of my last message was caused due the factory
defaults of my printer. The matter is that the USB port was disabled
by default, although the setup page didn't say so and although the
printer was detected thru that port.
Even if the USB is functioning in the printer, it won't accept
data thru the USB port unless it is explicitly enabled thru the
configuration menu (a kind of nightmare...).
If anyone has the same problem with the Lexmark Optra E312, I can
help about how to enable that port.
Excuses from my last post O:))
Ra?l