you did not clearly mention if you got it to work or not. If you pass the proper references to your last example, it should work.
Edit: I forgot to check the other thread first:
When doing it the way I proposed in my previous post, you don't need the "to more specific class" because all references keep their original type (while in your example the build array reverts the types to the lowest common type)
(I don't have LV 2012 installed so I can't quickly test your snippets)
