survey is not saving multiple choice answer with key press

So I am setting up an experiment where the participant views an email, then presses "S" if they think it is fake or "K" if they think it is real. I need to record the response time (which I have worked out and works exactly how I want it to), and to move them onto to the next question (which also works) however I also need to record the key press they used to answer the question, and this is not being recorded.