Does anyone know why the following lines return an empty array for parts that most definitely have bodies?

Set swComp = swSelMgr.GetSelectedObjectsComponent(SelNum)

varr = swComp.GetBodies3(SwConst.swBodyType_e.swAllBodies, Empty)

swComp is not empty. I can get the names of the comps that have GetBodies3 return empty.

Any help is appreciated.

Regards,

Patrick