I created this hair mesh in Zbrush

I imported it into Poser Pro, rigged it, conformed it to V4 and rendered it under the 3 default infinite lights that I get when I start up Poser.  This is the result.

 

As you can see, the hair has some sort of "indoor lighting" thing going on. Why is there light under the hair where there should be shadows? What's going on with that?  As you can tell from the expression on her face, Victoria seems quite concerned about it.