Quiz with drag and radio button options

In my Medical Terminology game/quiz, you have the option of dragging the word (text box)  to the correct x-ray or clicking the radio button labelled Not Shown. This works fine on the vocabulary which is shown. States and triggers control the radio button. However, I've one question in which the correct image is not shown. Clicking the radio button is the correct answer.

Setting it as a radio button question stops the text box from being able to be dragged. It will not move, so the student can easily deduce the correct answer. Since this is a level 3 game, I don't want deduction. I want to measure their skill. So both features, dragability and radio button must function fully.

Setting it as a drag/drop question hasn't returned a score if the radio button is clicked (which is the right answer.)

I'm not sure what I've missed. Any suggestions would greatly be appreciated.