Diaphragm Pressure Switch

Sir i have well calibrated diaphragm pressure switch whose setpoint is 12 kg. In addition to diaphragm pressure switch for high pressure tripping there is a bursting disc whose setpoint is 17 kg. The problem is that before the pressure gauge give the tripping command to the pump the busting disc brust. Sir what could be the reason behind the above stated problem and what would be the step to be taken to eliminate the problem. Is there is any way to increase the sensivity of the diaphragm pressure switch and to decrease it response time? Please help me to short out the problem.