Variables Question

Thanks Carolyn.  That does work.  However, I am dealing with a new issue now - I have attached an updated demo.  

I want the learner to have the option to use the mouse or keyboard. When they progress past the correct or incorrect layer - a trigger should add 1 to the sum of the appropriate variable.  the learner can click the enter button with their mouse or click enter on their keyboard.  Either one of those should add one to the variable value - unfortunately though, when they click one or the other, it adds 2 to the variable sum.  Any thoughts on how to fix that?

Thanks again!