Accessing a Shape on a Worksheet

Hi,

I am attempting to access a Shape or Drawing Object on a worksheet to
chane its Onaction and ListFillRange.

In VBA, you did this:
sheet.DrawingObjects("name").OnAction= "action"
sheet.DrawingObjects("name").ListFillRange= "ListFillRange"

In C#:
I can get access to the Shape object via
sheet.Shapes.Item("name"), which gives me access to OnAction, but not
ListFillRange.

I have tried this too
//gets all Drawing Objects on sheet
Excel.DrawingObjects d =
(Excel.DrawingObjects)sheet.DrawingObjects(missing);
return d.Item(name);

The problem is that the returned object is a COM__Object, and it cannot
be cast to anything useful (like an OLEObject).

Help!!!!!!!!!!!!!!!
I have spent too long trying to figure this out.