I tryed to move the sensors.
I tried a lot of things...It was always the same thing...
I decided to buy new ones
I received and tested the new ones (Amazon German seller) ...all are OK !
That mean I first received a set of 10 defective DS18b20 (chinese seller)
Unfortunatly, I received them 1 month ago and I cannot contact the seller (Store: Keli-te Store) because I got only 15 day to open a dispute
here is the Amazon German seller sensors ...