Rekordbox DJ doesn't send midi?

I'd like to control Rekordbox DJ with my Traktor Kontrol X1 MK1. Although Rekordbox receives midi from this controller, whatever I try, I cannot get it to send midi. At least, the Controller Editor doesn't receive it. In the Rekordbox menu I do choose send midi etc, choosing right channel and CC codes. Launching Ableton Live in parallel, and it immediately works (Controller Editor receives midi from Ableteon). I'd like to set this up because of the LED feedback on the controller.

Can you please assist?

Regards