Can't get models to load in game

[bmurph101]

So I managed to create some .esp files using FO4Edit; I got it to load everything except the custom .nif files I wanted for the weapons.

I was using .nif files from NV/Skyrim mods, but I figured a .nif is a .nif, though as some of you have already determined at this point I have absolutely no experience at doing this.

Can someone tell me what I'm doing wrong? Is it not possible to use existing .nifs? Or am I just missing something?

Thanks in advance.