There are a couple of items that can cause for this problem. The first would be the brake light switch. The brake light switch is used as a safety item to make sure that you have your brakes on when shifting to drive from park. If the brake lights are actually on, this is normally not the problem. The other item would be the shift lock control solenoid. This is an item in the base of your shifter that locks the shifter from being moved. This solenoid releases when the brake pedal is applied. There are some wiring tests to be done to be certain of this problem. I would verify that the BTSI, PT RLY fuse are all ok and that they do have 12 volts to them. This would be the first step in checking the power supply to the shift lock control system. Feel free to contact me with any questions or findings or if you would prefer a second opinion. Here is a wiring schematic so that you can see how the system is wired.