Objects selected in schematic, but car(selectedSet()) returns Nil

I'm trying to write a SKILL script to take the selected pins belonging to an instance placed into a schematic and create corresponding pins at the schematic level.  Sounds straightforward, right?  But after selecting a couple of these things in the schematic, I try to use the old standby css() or car(selectedSet()), but then I get a return value of Nil.  I haven't found any way to access these things.  When I do an "edit properties" in the schematic editor, I see the property name "instance pins", but then can't use the "select by property" setting the property to "instance pins" to select the objects.  When I use schHiSelectAll, and then in the pop-up window select only "pin" under the category "Instance Objects", these objects finally do get selected -- but again, css() returns Nil, and thus I can find no way to work with them in my script.  Any thoughts or help would be greatly appreciated.