Can't add printer to my PC

My printer is an HP DeskJet 960C. It's connected via USB to my Airport Extreme. I can't open Bonjour Print Service; I get this error http://i.imgur.com/ObbjJgv.png. I try the HP driver and it can't see my printer on the network. How can I get it working? I know it's an old printer but it still works and functions properly, I just can't connect to it for some reason :/

I'm on Windows 8.1 64bit