uhh, I just was too slowly entering the key sequence. Found a hint in
Thanks hawhill! I was just astonished that the launchpad.log-file turned into a zero length file every time I entered the key sequences slowly. So, I had the impression that something was going on, but a bug was in the launchpad setup on my kindle dxg.
Now, everything works fine. Just being fast – sometimes – is a solution ;-)