2008 Mercury Sable Parking Lights

Hello, my parking light fuse in my car blows each time I put in a new one and turn on my parking or headlights. My headlights, highbeams and fog lights work and come on just fine but I have no rear parking lights at all, however when I press the brake the lights light up as they're supposed to. My reverse, signal, and hazard lights work fine. Need some help, only problem I've had with this car