I used this tutorial to set up the NRF24 module: http://invent.module143.com/daskal_tutorial/raspberry-pi-3-wireless-pi-to-arduino-communication-with-nrf24l01/
It works, but only the first time after a boot. So I have to reboot the raspberry and can run the program again. But only one time. Than I have to reboot again. Does anybody know the reason...? It took me hours to figure this out and only by chance I realized that the code works... :-D
Thank you for your answers.
Best Regards Carsten