I just started using ATK/VNL, and it appears to be exactly what I've been looking for, but I can't seem to make the 3D viewer ever display anything other than blackness. If I run a transmission analysis exactly analogous to the one in the tutorial and either drag a device configuration into the viewer window or click "show" on a transmission pathways object, the viewer doesn't show anything (even though, for the transmission pathways object, the progress bars that pop up show that the arrows were in fact calculated). If I right click and select "Properties" in the viewer window, the only plot listed is "Graphics Scene." I expect I'm missing something obvious...