Rear Brake Problem

One day, i found vitara rear brake is not working well, when at parking position, brake pad always stick on it's drum, and brake oil tank need to fill at least half tank, once a week. So it must leakage problem. Rubber boot problem...... After open brake drum, i replace master brake piston seal, and its rubber boot. Just make sure the rubber boot is good and tight. I buy rubber boot for Isuzu Panther at nearest shop. It's hard, and tight enough for Vitara master brake cylinder.