Hi and welcome to Arturia forums.
Congratulation with your new controller.
Are you also new to Cubase and DAWs in generel?
Have you setup your controller in Cubase like you can read about in this two links?:
https://www.arturia.com/faq/keylabmkii/keylab-mkii-tips-trickshttps://www.sweetwater.com/sweetcare/articles/connect-midi-keyboard-cubase/You need the controller to be setup both as a Keyboard and as a Control surface.
Also if needed, then be sure your controller is selected in Analog Labs lower toolbar.
Without having Cubase or a Arturia controller, then i guess the solution to your issue is to be found in this.
In generel i also suggest you consult your manuals to understand how things work, when things are setup.
Many informations can allready be found on the web, including in Arturia forums.