Yeah ... Solved ... I had a way to work around my problem but I still kept at trying to understand what was going wrong during almost 3 hours . Ok this is not great to progress in your dev, but it s still a good thing to do in general you may say. Yes. Of course . BUT . See what I added after 3 hours of trying everything but that..
That s right, maybe it could be interesting to know what object was causing the problem .. The rigidbody? The empty gameObject?? 
Oh Yeah right , there s this enemy that I keep Ignoring wich can trigger the boxCollider. Nice Work!
Haha anyway thanks for everyone who took the time to answer me, I wish you a good jam and I hope I ll have something done at the end.