Captivate 9 Knowledge Check Decrement score

I am using Captivate 9 and have two knowledge checks in a module. I'm using knowledge checks (KC) so that the scores are not recorded to the LMS and so I can have two separate sets of questions in the module. A score will be kept and displayed at the end of each KC though.

I would like the KC to work such that you get 2 attempts at each question (5 questions), a correct answer gets 2 points but an incorrect answers gets -1 point.

I've set up a variable for each KC, score_1 and score_2. I've set up a script so that neither score can go above 10 and below 0. I can get the scores to increment by 2 points and have 2 attempts at each question but I can't get the scores to decrement by 1 on an incorrect answer.

Is there any way of doing this in a knowledge check please? Thanks.