Seems like you are drawing with black every tick and only create 1 point at mouse.x,mouse.y while clicking the green sprite..
If you could remove the green sprite during the program, you'd see the green point you drew below it..
I guess you'd want a global variable (text) set it to the colour-name you want on clicked sprite and draw with the colour Variable every tick instead of black..
Both "every tick" conditions in event 1 and event 2 are useless by the way..
Event 1 is a triggered event so it will only run once when true..
Event 2 will run every tick its conditions are true, regardless of the every tick condition you added..