Using digikam as DAM, editing in rawtherapee via the digikam editor

Dear digikam and Rawtherapee users,

I would like to manage my pictures, movies etc. in digikam and edit the RAWs with rawtherapee. Therefore I have configured digikam so that the image editor opens the image in rawtherapee. So far everything works, the respective RAW is opened in rawtherapee and after closing Rawtherapee the edited image appears again in the editor of digikam.
Now my problem or my question. How can I transfer the edited image into the album? The buttons “Save change” or “Save as new version” etc. are grayed out. Only “Close Editor” is active and clickable. If I select only “Close Editor”, then the edited version of the RAWS is not inserted into the Digikam album, not even as a JPEG. Do I want too much, this possibly does not go at all?

Thanks in advance for your answers.