Hp 7310 driver download duplex printing windows 7

[fdiba]

Clicking on duplex (2-sided) printing in Printer Preferences, error message states duplexer not attached.
How to overcome this error message and print two-sided

 

[das_stig]

Fit a duplexer unit, not normally fitted as standard, its a big box hanging out the back.

 

[fdiba]

Thanks, but by saying that there was an ERROR message, I presumed that everyone would understand that the duplexer attachment IS ALREADY FITTED, yet I still get this message and it will not print duplex.