Digikam: edit image in RAW format

I have Kubuntu (22.04) running as OS. DigiKam is version 8.1.0. Darktable is in version 3.8.1
In the Settings of digiKam I have set in the ‘Image Editor’ the ‘RAW Behaviour’ to: ‘Always open the Raw import tool to customize settings to: Raw import using DarkTable’.
But when i open an image in Raw format (DNG) I get only a jpeg preview. DarkTable does not open.
What went wrong?