CompuServe Messages

Hi to all, I have a little problem with raytraced shadows. I have a archictural scene with 180,000 triangles. I use raytraced shadows with a bias of 0.01 and a pixel size of 1.5. When I render the scene I see wrong shadows. Sometimes a shadow is interrupted, uncomplete. Sometimes the shadow is far away from physical correctness. I thought I can manage it with the shadow bias but it is already 0.01. Any suggestions? Michael