There are separate acuating switches and wires for each brake going to the same light. The front is in the lever/hinge area. The rear is near the pedal/actuator likely connected with a spring or stiff wire. The rear is adjustable and sounds like the light switch is adjusted to come on too late in the pedal travel. The front switch or wire may be broken. You can usually hear the front switch click on and off with the lever if it's really quite around your bike.