To kill an existing material in poser, go to the material room , select the base node (posersurface) , right click, select inverse, then press delete. That leaves you with ONLY the base node . Check that specular and transparanct and ambiant are all set to 0 and black color.

Then attach your image map node ( new node>2d>image map) and attach that to the diffuse at the top. then attach the same image map to specular, and set specular color to white, and set the dial to maybe 0.3   Work your way up adding bump or dispacement .