No Sound with RbPi-4 and Hifiberry Amp-2

Volumio 2.703
Raspberry Pi-4 1Gbyte RAM
HiFiBerry Amp-2 vers.1.1
Log DLD Key:
Error message in “volumio.log”
2020-02-19T12:35:43.157Z - error: Cannot set ALSA Volume: Error: Alsa Mixer Error: amixer: Unable to find simple control ‘Digital’,0

Can play music via Sound-Jack but not via Amp. Tried several configurations e.g. “HifiBerry DAC plus” “- Amp” different Mixer settings
For Mixer settings I have only the option [Hardware|Software|None]

Please suggest what to try next.

Thank you very much in advance