Occlusion Culling Problem

I am currently using SolidDesigner/Annotation version 9.1.0.15 on a Pentium 3 600 with Windows NT 4. I recently had an nVidia Quadro4 550 XGL video card (64 MG of memory) installed which claims to have second generation Occlusion Culling capability. When I tried to enable the Occlusion Culling function from SolidDesigner under the Graphic Settings command, it is grayed out not allowing me to select it. Does anyone know why the Occlusion Culling will not work as advertised? I have contacted CoCreate and nVidia but they haven't been able to help me.

See my answer in the "SolidDesigner" forum.