interesting....
so it was that exact node after all?
Now that I know the exact issue it should be easier to deal with. Thank you.

actually i think I already have your shader set....or someone's shader set..... but doesnt the python have to be recalculated if the primary light source changes? Since I mostly work in animations that would be an issue. Maybe I dont have the latest real skin shader product. Which is the best currently available?

anyway thanx for the info =)

Im curious. though...
how did you discover and isolate such a (seemingly) minute math bug? Do you work from the code side?