Printing to the wrong USB port (HP Deskjet 6540-50 series)
If the computer is configured to use both the printer's back USB port and its
front
USB port
, then you might be printing to the wrong port.
The computer has two versions of the printer driver: one for the front USB port and
one for the back USB port. If you are connected to the back USB port but select the
printer driver that is associated with the front USB port, the printer will not print.
Click File , and then click Print to open the Print dialog box. The Print dialog box
displays two versions of the printer driver. Select the version that is associated with
the port to which you are printing.