Iterate read-only properties in Delphi

Question

I'm trying to iterate through a COM object class to list all the properties, but readonly properties are not coming through. The class is defined with many properties but here are a couple ...

property RecLineSpacing: Integer dispid 123;
property RecLinesToPaperCut: Integer readonly dispid 124;

The code I'm iterating with is ...

function PropertyValues(const AObject: TObject) : TStringlist;
var
  PropIndex: Integer;
  PropCount: Integer;
  PropList: PPropList;
  PropInfo: PPropInfo;
const
  TypeKinds: TTypeKinds = [tkUnknown, tkInteger, tkChar, tkEnumeration, tkFloat,
    tkString, tkSet, tkClass, tkMethod, tkWChar, tkLString, tkWString,
    tkVariant, tkArray, tkRecord, tkInterface, tkInt64, tkDynArray, tkUString,
    tkClassRef, tkPointer, tkProcedure];
begin
  result:=tstringlist.Create;
  GetMem(PropList, SizeOf(PropList^));
  try
    PropCount := GetPropList(AObject.ClassInfo, TypeKinds, PropList);
    for PropIndex := 0 to PropCount - 1 do
    begin
      PropInfo := PropList^[PropIndex];
      result.Add ('['+propinfo.Name+']');
    end;
  finally
    FreeMem(PropList);
  end;
end;

In this case the output lists RecLineSpacing but not RecLinesToPaperCut. Any idea why this would be?

Thanks Terry