doorsx11x

Hi everyone. I've had my '01 S4 since '05 and doing my first rear brake pad replacement. The passenger side was easy. I rented the caliper tool and screwed the piston clockwise while pressing it in. Did not remove the parking brake. No issues. Now on the drivers side however the caliper is stuck. Doing the same, screwing down clockwise. Parking brake is still on the caliper but the parking brake lever isn't engaged at least. With all my might, that caliper is not budging. What am I missing? Do I need to remove the parking brake? Any tips? Thanks