The game crashes when i try to give my actor a weapon from my mod
Also, vanilla weapons are ok for it.

Weapons have to be loaded before the actor. This might be your problem otherwise I need the error

I used IncludeFile = before, but now i put the weapons ontop of the actors in the index.ini

You wrote something wrong somewhere, that's what that error means

So i did, it's fixed now, thanks anyway.