Having issues with numeric variables - Markers at progress map not reflecting performance of learners

I have a current assignment requiring me to build a package to train learners to spot errors, and basing on their selection (of errors), they have to decide the next actions to take.  There are total of 16 mini-exercises, and in each mini-exercise, learners will go through the same repertoire (spot error, identify the error, choose action).  Each mini-exercise will end with feedback, informing the learner if they got that correct or wrong.  There is only 1 correct answer for each mini-exercise.

We put in a progress map to track the "result" of each mini-exercise.  The marker in the progress chart will reflect "correct" or "wrong" depending on how the learners fare for each question.

We use numeric variables - default value of each variable is 1.  If they got the mini-exercise correct, trigger will +1 to variable;  if incorrect, trigger will -1.  Then state of markers on progress map will change depending on value of variable.

Simple idea, but the markers on the progress map are not changing!  And, we couldn't figure out what's wrong (*sob*)

For simplicity, we attach only 1 exercise (Marker #1).    Appreciate all your help in advance!