Invisible Mesh in - game

[ThyLD]

Hi, I'm trying to port an armor set to Skyrim SE, I have done it multiple times for Fallout 4 but for some reason I can't get this to work now.

I've converted the files with blender to .obj imported them in OS, added bones then exported them as .nif and assigned textures with Nifskope and fixed some proprieties using refrences from  another working .nif.
When I equip the item in game it's invisible.

 

Could someone take a look at it and maybe explain what is wrong with it?

 

Here is the file:

 

https://www.dropbox.com/s/udopszub447ly9p/Skyrim MOD.rar?dl=0

EDIT: FYI the file is the helmet, i'm starting with that.

 

Thanks in advance.