…a side thing; i’m using Lenovo ThinkPad tablet and I was trying to pair with the Lenovo ThinkPad keyboard. It was confusing! I did it before and totally can’t remember how I did it. The manual doesn’t make sense, google is the way!
So the trick? Find the device, and it should ask for the passcode. Click the link just below the box if the passcode is not known; it should give the passcode. Take a picture of the passcode. Type it in the box (using the touch screen keyboard) and also type using the external keyboard. It should pair then – or maybe you actually just need to type using the external keyboard *shrugs*