GetJSObject() returns error "Value does not fall within expected range"

I'm trying to pull comments from an Acrobat XI document using VB.

app = CreateObject("AcroExch.App")

doc = CreateObject("AcroExch.PDDoc")

jso = doc.GetJSObject()

where jso (an Object) under 'message' says "Value does not fall within expected range". I recently updated the framework from Microsoft.NET 2.0 to 4.0 and was previously using the Adobe Acrobat 7.0 Type Library, which has been updated to the 10.0 type library. Somewhere, something stopped working, and I know the document has comments in it because I can see them when I open the document.

The next call is jso.getAnnots() which returns nothing.

Any help is much appreciated.

Thanks,