Hi Paul,
Thanks for reaching out to us, I am sorry this is not working as expected.
I would like to start by asking if you have already installed the drivers available on our page here ( https://plugable.com/drivers/displaylink )? Additionally, when connected to the computer, does the green USB LED light up ( right under the blue power LED )?
Thank you,
Pat
Plugable Technologies
www.plugable.com/support