Communication with a Keithley 617

I'm currently trying to use an old Keithley 617 using the National Instrument UBS-GPIB HS adapter.

I installed all the required NI drivers required to use it. However, whatever command I use (e.g. "*IDN?\n"), it returns the value that is displayed on the screen of the Keithley 617.

I attached a print screen showing the problem.

It would be of much help if anyone knows how to solve this problem.

Emmanuel