Hi, for the Transport Window Functions do the following :
that works for Keylab 49 - 88 :
Open in Cubase Transport > Project Synchronization Setup > Machine Control Input section
Click “MMC Slave Active”
In MIDI TimeCode Source Section and select your Keylab Keyboard
MMC input : ALL MIDI Input
MMC Device ID : 127
Thats all
All other Cubase functions you can generate with the Generic Midi Device Manager
CU
Ruedi