The shadow is there becourse the transmap isn't 100% black or becourse it isn't at 100%. Check the transparency settings, and look out for any falloff other than 0.0 Some versions of P5 had the falloff at 0.6, this could give the shadow you're expiriencing.

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.