Actuators are open but no flow

Really stupid question: Have you ever turned that black little wheel on the sight glasses all the way open?
You can easily open the control valve manually by turning the upper part (blue) to "manual".

Yes, I have, unfortunately no change

Is the pump running?

And a few more words ...

Yes, it is running, in the ground floor the heating circuits also warm up. I have already turned the pump up to full power, but no change in the attic either. The pump is one from Wilo.

Attached is a flow meter

Then write exactly "What has happened so far".

please write down everything that was done, why, how, and for what reason…

The pipes in the attic HKV were dirty so that the set flow rate could no longer be read. I then thought I would clean them once. As a test, I did the whole thing in the basement on one, and everything worked without problems. There is flow, and the floor as well as the room get warm. I then closed the supply and return in the attic, removed and cleaned the pipes, and screwed them back on. After that, I reopened the supply and return. Then I opened the actuators again, but since then no flow has been shown in the flow meters, and the heating circuits in the attic are no longer getting warm. Attached is again a picture of how the flow meter looks in the basement and in the attic, left attic bathroom, right basement

Look at the flow meter in the DG, there is a red cap missing that connects the spring inside with the white tube. Maybe that is missing and that is why.