Hi!
I bought a Roland A-300-PRO.
I use Windows 10.
I’ts not shown in Cubase OR the Device manager.
The problem:
I plug in the USB from the computer to the Roland Keyboard. The power on the keyboard is on, but it’s not noticed by my computer what so ever. Tried different cables but nothing helps.
Any tips? 
Anyone?..
You downloaded the win10 device driver, installed it, basically followed the win8 instructions on page 12/13 of the manual, turned the power switch to USB, then what? Did the notification mentioned on page 15 appear? If so, after reboot, you should be seeing it under “sound, video, and game controllers” in device manager. If not, then it’s a Roland problem. If it does appear in the device Manager, but not in Cubase, then it’s a cubase problem. You’d want to check “Device setup” in Cubase and read the part in the operations manual that deals in MIDI ports and/or remote devices.
You are missing one key element, the most important element for any external device: The Driver.
Thanks for the replies. When i plug it in, no driver is installing. It’s really weird. @Colinpark No notification at all, can’t see it anywhere 