I've noticed some situations where this happens:
- You try to make an item dual weird, for example mesh name="Blade04x2", mesh name="RocketLauncher01x2", and your models do not support dual wield for that type of item. If this is the case, shouldn't be hard to fix it, I think that stuff is defined in weapon.xml in model.mrs. Not sure though, as I haven't messed much with models.
- You put an item in a slot that is not compatible with the item type. Example: weapon="frag" slot="melee"; weapon="katana" slot="range"
- I believe it also happens when, for example, you define an items mesh as a melee mesh. and define the weapon type as a ranged weapon and the slot as a ranged weapon. So, what I mean is, the Weapon Type must be a type that is associated with that slot, and the mesh must also be one that is associated with that slot. No rocket swords.
There are probably more ways this can happen, but that should give you an idea. Also, note that the syntax I used in my examples may not be correct. I advise you to study the model files if you want to break any of these prefabricated rules.
I'm trying currently to create a pistol that shoots rockets. The pistol shows up, since both pistols and rockets are ranged weapons, but the type of rounds fired seems to be defined in the mesh, so if I want to make a pistol that fires rockets, I guess I'd have to create a new mesh that is a copy of the pistol mesh, with the ammo information replaced with that of the rocket launcher mesh.