For a multiple Choice question ".shown" will not give you the one das has been picked. Shown basically shows the text of the answer/subquestion, not the code. That is what shown does. For single choice question it is the same as the picked one, but not for multiple choice questions.
For multiple choice questions you can find out if a subquestion has been marked by checking if it has a "Y" in the database.
So what you could do to show the subquestions in a multiple choice question that have not been picked is check one by one if it equals Y or not.
Something like this should do the trick (untested):
Code:
{if(questioncode_subquestioncode != "Y", "questioncode.subquestioncode.shown", "")}