Counter of clicks on a score

Hello, I am building an experiment where it requires that the number of clicks made on three buttons (A, B and C) be displayed in three markers (A, B and C).
Does anyone know how it is possible to make the number of clicks for each button be reflected in the scoreboard?
Until now I have this progress that I attach, however it gives me an error because an attribute of the marker is not well defined

botónes.psyexp (43.1 KB)