break light blow out!!

my break light keeps going out! the tail light still works , but no break light!and i have replaced three times already!
i checked conections, bulb type,bulb fitting in socket

any ideas why?

When you checked the connections, did you trace your brake light wire all the way back to make sure it's not grounding out against the frame or some piece of metal along the way?

Sounds like a dead short to ground somewhere in rear brake light circuit.

does the tail light assembly have a rubber dampener?

vibration kills the brake light element. it glows with more power and gets hotter than the running light so the coil of wire breaks easily.