I will assume that you did the entire scene in Poser and brought it over to C5 for rendering.  I have tried this a few times, but you get much better results if you do just the characters in Poser and the rest of the modeling in C5.  The Poser skin system is pretty basic and hard to use compared to C5.  BTW I love the image and can hardly wait to see your final version.  You may wish to adjust the gamma a bit, it is visible but you can barely make out anything other than about 2/3 of the characters and some glints off the metal bars.