My Note 4 S pen doesn't work

[AC Question]

From what I read in the comments here i don't find my problem.the problem with my S pen is that air command works when i pull the pen out,but the pen doesn't command them.In other phones it works.this issue happened since i changed the motherboard because it was broken.the phone use to work great and still works great except the pen...anyone has a solution for this? Thnx Eddie Note 4