Ohh, I found it, my fault - I did not notice, that there was a version change but accidently saw it. I installed the new 1.2 Version on my DU and had an older version 1.12 on the DP.... uninstalled the 1.2 DU and installed the 1.12 version and it works.
So, after all, disregard this thread or take it as part of the experience.
Regards,
Oliver