97 Intrepid Parking Brake Adjustment.

My 97 Intrepid failed safety inspection this morning. They said the parking brake "will" hold the car at idle when placed in reverse but "will not" hold the car at idle when placed in drive. It does coast forward when you do this. I took the rear wheels off and both sides have good pads on rear disk brakes.
Does anyone know how to adjust the parking brake so that the brakes will hold when placed in drive? Thanks.