Thank you for your reply.
It’s a fader on keyboard that is connected to the MIDI in of the H9000R.
The fader sends controller data on controller #21 channel 1, as I verified on a Midi monitor.
I’m mapping by putting a parameter in learn mode, moving the fader and apparently the incoming data is seen as program change on MIDI channel 2.
The same happens when I send controller data from MAX.