NIF Retexture Help

[Kpheonix57]

I'm trying to create a standalone version of the fire wall NIF where the flames burn black, instead of the usual yellow/orange/red color. I thought it'd be pretty simple, but apparently it's not. I extracted the firewallfx01.nif (NIF the kit points to for the actual ground hazard) from the Skyrim - Meshes BSA file, and renamed it to avoid conflicts with the original spell in game. I opened it up in NIFSkope, and made the change in the "80 BSShaderEffectProperty" block within the NIF. Specifically, I changed the Gradient Texture field to point to the new texture file I've created. Once I added the new NIF into it's own hazard form within the creation kit, I tried to preview it. When I do that, it causes the entire creation kit to crash. Anyone mind pointing me in the right direction here?

 

If I were guessing based on the creation kit's reaction, I've probably managed to corrupt the NIF file in some way, but I've no idea what I might've changed to cause that. I'm a total noob when it comes to NIF editing, so I'm finding myself very overwhelmed. In case I'd accidentally changed something incorrectly the first time, I've already tried redoing the same process again and gotten the same result. Also, I'm quite sure the issue isn't with the texture file itself, given that I'm using this same texture file to successfully re-texture other flame effects already.