Here's one thing to remember about button sets....and I get caught doing this all the time.
I have often used button sets for creating various slides, questions, interactions. Then to make life easier, as we all do, I copy that slide and use it multiple times. I tinker with the slide as needed for the next question/interaction, but then I forget to ensure the button set is set propperly for the next interaction.
Example: The first one I create might be a "pick one of 5". I design it all up, pick the right answer of the five and I'm done. The overall set-up of this first slide is exactly what I want for the next one so I copy the full slide. The next slide is a "pick many of 5". I change up the wording, the answer choices, I pick the right 2-3 answers.....and I forget to turn off the button set. When the course runs....the user can only pick one of 5 instead of many.
It seems simple and silly to do, but when you get into making courses quickly and look for those time saving steps of copy and pasting....you sometimes forget, you didn't mean copy and paste everything. :)
Here's my little posting/screenr about this:
http://bit.ly/1mEkGIP