I have Yamaha DJX connected to a pc via Creative Fatality X-Fi Midi Ports
The devices show up in Device Setup but there is no evidence of any Midi traffic in or out of Cubase
What version of Cubase do you have? Older versions will not detect a keyboard unless Cubase is started before connecting and turning on the keyboard.
Also… are you trying to play/record on an Instrument" track? If so, then you will need to set your keyboard to “local off” then assign a VSTi to the Instrument track and choose a sound from what is available in the VSTi.
Regards 