Washed your bike or ridden in the rain lately ? The button is a momentary contact type. If nothing happens, the button you pull in may not really be making the trip. Try spraying some Tri-Flow aerosol into the switch housing ( not WD-40) although others have used WD to make switches work after getting wet or just time/use will deposit traces of carbon. Enough to interfere with positive contact. Some people use contact cleaner ( that dries out right away) but it may harm paint. Tri-flow won’t harm any finish, plastic or Paint. It is a aerosol Lube /Dielectric Spray w/properties that help make contacts complete the circuit again. Hope this helps. If not at least you can use the Tri-flow to Lube clutch/brake levers,shifter linkage, brake pedal pivot, kickstand pivot,Etc. It also smells nice and is food grade.