You're trying to get diffuse-reflected (i.e. near-surface scattered) light to show those colors, but you're connecting them to the attenuation distance. Won't work - it can only alter the distance it takes to fade the deep scatter, as I demonstrated.

Instead you probably want to not use the Physical Surface, as the starting amount (ratio, aka color coefficient) of scattered light is not under your control and you have no place to plug this map in.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)