On of 4 layers won't render

When either rendering an image in Blender or exporting the .fbx to Unity, I can’t get the “skin” layer of my character model to render. I’ve trouble-shot this for a bit now and I can’t seem to find the missing link. I feel like I am overlooking something simple. All of the textures and materials across the other objects (clothes and eyes; the armature is on a separate layer as well) seem to have the same options and similar values selected so I don’t think that is it. Can anyone offer any suggestions? I would greatly appreciate it!

I’m trying to upload the .blend file but it won’t confirm the upload.

Many thanks!

Check the image in your skin layer and make sure that it’s not zero alpha. Other than that it’s hared to say without at least a screen shot posted.