WMS layers in ArcScene

Quoting the ArcGIS 10.1 for Desktop help, "Web Mapping Service (WMS) services can be used in ArcMap (as well as in ArcScene and ArcGlobe) as map layers." However, I can't seem to figure out how to get them into ArcScene. They show up in the Add Data dialog box (whereas other types of web services don't show up at all), but when you click on them to open up the layers, they will not load. I've also tried drag and drop from ArcCatalog, which you supposedly can do, and ArcScene says it cannot add this layer. Any guidance would be appreciated.

Jeff Doty
GIS Specialist
National Park Service
Midwest Regional Office-GIS