Why would 2 of 3 brake lights on your 1996 Hyundai Accent stay on even when car is off and parking brake is not engaged?

After replacing a brake light bulb I found that when you put the headlights on all the brake lights come on as well. Did this happen to you? Does any body know where I went wrong? You have either fitted the wrong bulb, or you have got the correct bulb incorrectly fitted, check to see if the front sidelights illuminate when applying the brakes (obviously with the lights switched off)....recheck the bulb and fitting :)