taillight help

[yellowhonda400]

ok i got astock tail/brake light for xmas. i put it on yestrday and everything works fine besides my rear brake. when i press it the brake light wont come on. the fronts work fine and engage the brake light but the rears dont. anyone know why this might be happening. everything is hookedup right. p.s. when i got the quad it did not have a taillight.

[miles Machine]

does it have the rear brake pedal switch??? if it does make sure its adjusted right or the spring is not stretched out