De-synchronization with Collisions

So now, that I move my characters with AddForce, so It can take in account collisions, they actually de-synchronize themselves between two instances of the game, because of it.

I don't understand why?
Because, I'm using TrueSync components ; I'm moving my characters with the TrueSunc methods, they collider well, untill the collision occurs differently between two instances. It doesn't seem deterministic then.