Hi there

 

As above I would add at least one point light above the ceiling or I would use Infinite light,rendering enclosed space as is interior is bit pain with Poser,you still can get splotchess

 

Here are my renders which I've rendered with Poser Pro 2014 and IDL,,in this renders I've used above D3D Firefly settings and light setup consist from 2 infinite lights(One acting as sun with 42% and one without the shadows set at 40%),1 IBL(Light have set intensity at 30%) and 4 ceiling lights(Point light set as inverse and intensity 5%),Gamma Correction OFF and Sphere from Bagginsbill and HDR picture from HDRlab and TrueForm Contemporary Bedroom

Thanks,Jura