MIDI In problem with Moog Grandmother


I want to use the Moog Grandmother to play liveloops in the pyramid.
I tested it with the Arturia Keystep and it worked fine with every MIDIchannel … there is allways a input signal on the Pyramid.
But with the same settings on the Pyramid there is no MIDI signal with the Grandmother as the MIDI Keyboard. First I thought the Grandmother doesn’t give out some MIDI. But I pluged the MIDI Out to a o-coast synth and there was MIDI. I could play the notes the same way as with the Keystep.

Does someone have a idea why the MIDI out signal of the Grandmother isn’t accepted on the Pyramid but on other synth devices?
Or better … what I have to do that the Grandmother could be the MIDI keyboard input of the Pyramid?