Not sure if this belongs here or in CS. Anyways, I was looking at some other vampire head meshes in nifscope and they both have 2 source textures so I think this has something to do with it but I'm not 100% sure. Anyways, I can't figure out how to do it so that it actually works once I become a vampire. I tried making two source textures (regular face and vampire face) with one mesh but that didn't work. Any ideas?

Not sure if this is your problem, but vampire heads need the mesh to be named a specific way.
b_v_argonian_f_head_01.nif

The "b_v_" is what is important. Without that the head will not be recognized as a vampire head.

It didn't work, but that's useful info.

I'll detail what I'm doing so everybody has a better perspective on how I'm going about going about this....

IN NIFSCOPE

....upload mesh 'Face Brown Eyesxxxx'

Original source texture - 'Face Brown Eyes'

.....insert-->sourcetexture 'b_v_face02' [2nd texture]

***I also have another mesh named 'face brown eyes' which I also link to the source texture 'Face Brown Eyes' but that doesn't use the vampire texture.

IN CS.....

I'm linking the playable head mesh as 'Face Brown Eyesxxxx' and checking to see if it works, then linking it to 'Face Brown Eyes' and neither works

My vampire head is linked to the 'Face Brown Eyesxxxx' mesh

EDIT: I just realized you said the mesh needs to be named that, so instead of Face Brown Eyesxxxx it is now b_v_face01....I am still encountering the same problems, however.

Do you have to specify the race somewhere in the mesh or texture?

I'm asking because I'm creating this for a new race, and I literally copied a vampire mesh over from better heads and just replaced the texture files to ones I wanted and it still didn't work.

I also just linked the exact same mesh for the imperial vampire to my new race (it's the exact same as an imperial just with altered size and stats) and the face shows up for the imperial vampire, but not for my race. Somebody please explain this to me, this is extremely confusing. It has to be a race issue, but I don't know how I am supposed to fix it.

In the CS, you just give the NPC a standard Head. The vampire Heads should not even appear as an option.
And than through the vampire script they are given the vamp Head. (it's just hard coded that way)
A vamp Head will never appear unless the NPC is a vampire.

So yes, Race is a factor. And if I'm starting to remember correctly, the mesh ID needs to replace the vanilla one. Meaning, it has to be the exact same name.
You cannot choose which Head a vampire has. Each Race has one, and that is applied when they become a vamp.

I'm pretty sure that's how it works.... Hopefully someone can confirm or correct me.

Sorry, I meant the new race was for my own character. I am trying to make my new race character have a vampire face, but it never works. I just get a blank space where the head should be.

Maybe you're having more than one issue...

Some vampire heads made by modders have 2 textures because one is for the face itself, and the other is for making their eyes glow in the dark. It's possible you modified just the second one.

Another problem is with how vampirism works in the game.

If you become a vampire, the game will look for the first head set as "vampire" for that race and use that (any other head that may eventually be present will never be used).

There a glitch, though.

IF that head and/or its .NIF file is named anything else than "b_v_racename_F_head_01" for females or "b_v_racename_M_head_01" for males, than the player will appear without head.

It's actually just a minor inconvenience: remove/equip a piece of clothing and the head will show up correctly.

Not sure, but I think this problem presents itself every time you start the game... once you put on/off something, you are fine for the rest of that session.

It's not any of those things; I have no idea what the hell I am doing wrong. I have tried everything I can possibly think of to remedy this and nothing has worked. I'm going to try downloading another race mod and just replace all of the files for that one with my the graphics I want, and if that doesn't work and nobody has any more advice for me I am going to give up.