when calibrating I put the gas into the analyser , the measurement results deviate quite a lot from the setpoint, then I press start calibration, the result pulls close to the setpoint value, but then it is still wrong. 

there is another problem is that when change the gas into the analyser with a different concentration, the measurement result will be quite large and it will take a long time for the value to return to a stable level, for example I attached is putting nitrogen gas read the result 6-7%, then put in the air, immediately measure up to 200% and it takes about 5 minutes for the result to return to a stable level of 25%. Help me, please!!!