APC40 fail to open in Max for Live

Hi everyone,

I saw this question asked on some topics but somehow nobody was able to find any solution

I maped my APC 40 on a max patch to control several parameters of a drum machine that i'm working on.
The mapping worked great until i saved it as a max for live device.
Most of the mapping is still functionnal but when i open the max editor in M4L i keep getting these messages

"midi_mme: error 4 opening midi input device Akai APC40"
"midi_mme: error 4 opening output device Akai APC40"

Asi said most of the mapping is still functionnal but the patch isn't able to split the midi channels of the controller anymore.
That means that i have every column of parameters (clip launch, clip stop, strack selection, activation, solo/cue, record arm and volume control) is assigned to the first midi channel instead of having them splitted onto 8 midi channels.

I can't find the solution anywhere, i tried to desactivate the automatic mapping for the apc in max but the problem is still here.

It's obviously coming from max because Ableton is still able to tell appart the differents midi channels, so it must come from that error n°4.

If someone was able to overcome this problem and would share his solutions that would be great.

Thanks a lot

Théo