@score number resets between answers

I want to keep track of how many times the respondent has answered "yes" to a yes/no question. So, I created a loop that increments the score every time the respondent presses "yes".

However, the score data resets to zero when the respondent returns to the original point.

Code:

S1: What is the shape of this picture?

• A: a square
• B: a circle
• C: a triangle

The correct answer would be C, leading to S4.

If the respondent chooses A or B, it leads to S2.

In S2, the respondent can choose whether they want help or to try again.

• yes: I want help
• no: back to S1

Code in S2:

If: incorrect, need a hint? is Yes Add 1 to @score If: incorrect, need a hint is Yes go to S3

If: incorrect, need a hint is No go to S1

Now, coming back from the loop where we added +1 to the score to the original S1, @score is nullified. Why?