Problem/Errors: Commissioning Guide | Step 2 - Build plate prep.

Hi Folks, pretty new to Klipper based 3D Printing, build my V-Core 4 300mm and now i trying to follow all the Steps from the Commissioning Guide. I always get Errors when trying to use the Command "BEACON_RATOS_CALIBRATE", i just can't get past it.

Wanted to askif somebody has a clue what i can try to solve it, for info i tried with RC2 and upgraded to RC3, made no changes to any config at this moment.