Hi Zoltan,
I think I was not clear enough.
My problem is not how to map midi in general but this specific funtion which allow only 1 button (for both "+" and "-"):

- Capture d’écran 2018-05-01 à 09.46.18.png (12.51 KiB) Viewed 10781 times
I know that I can had more buttons to one function in R6 but the main problem is to set 1 button for minus and one for plus.
I've tried with Toggle, Value and Velocity options that are proposed but nothing works like a simple click with the mouse.
It's the same here of course :

- Capture d’écran 2018-05-01 à 09.58.15.png (13.13 KiB) Viewed 10781 times
Thanks