Ok, now I understand the problems.
In Germany there ist still a mix of analogue and digital RF sources around, so that might be the difference.
The receiver are still supporting the analoge signals, but it will find an end when the last "old" signal is turned off.
I think then the "new" TV sets will then include a standard, no frills, digital TV-Tuner and that's it.
Maybe I should buy some TVs as spare for later?
Thanks for the infos!