Have you tried boosting the dome's ambient setting? Normally the ambient colour of something is black or at least dark, but on some things a brighter ambient is needed. I know I always have to boost ambience when I use the Cyclorama in P5 so I would guess the same applies here :o)

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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.