Why is my mouse's right click sometimes doesn't work?

Why is my mouse's right click sometimes doesn't work? I have a Acer Predator Cestus 300 mouse that I’ve used for 6 months since. Recently, it’s right click seem to be broken: sometimes when I press it does have the “click” sound but it does not work. When it happens, I have to kinda press it harder to make it works again normally but I worry if I continue to do this I will brake that right one.