By default, Poser will try to use the shader node information even when using the P4 Renderer. For best results go to Render Settings, click on the Poser 4 tab, and make sure to check the option for "Ignore shader trees". This will also speed up the rendering.
After all, if you want to use the shader nodes, just use the FireFly renderer.

Quote - Why you don´t try Firefly? It´s a very good  render-mashine with much better results than the Poser4 render.

I tend not to use the FireFly Renderer unless I need to, basically because a number of my characters and materials were "tuned" to the P4 Renderer and they don't look the same using FireFly. My Tabby character uses a combination of Object Color, Ambient Color, Ambient Value, and a specific set of lights to get just the look that I want. The FireFly Renderer reads the Ambient Color and Ambient Value differently and the character looks washed out.
I've tried numerous adjustments since P5, but the P4 Renderer is still the easiest option.

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