interesting little game! Unfortunately, only about 1/4th of my clicks seemed to register..
I think there are two click mechanics going on -> visual and non visual. Depending on the level, not every click gives you visual feedback of the liquid decreasing, however, you get audio feedback for every click. Would be better if the clicks were always registered visually, though, and should be easy for the developer to implement.
You are totally correct. Maybe I'll fix this, as some people might play without sound enabled.