ADXL372 Instant-on threshold problem

Hi,

I want to use ADXL372 sensor in instant-on mode. In my code, configurations are as follows.

-High instant-on threshold(30-40g)

-I2C=1MHz

-ODR=1600Hz

-High-pass, low-pass filters are disabled, filter settling=16ms

For instant-on mode, datasheet says that when an impact beyond the selected threshold is detected(30-40g for me) the ADXL372 switches to full bandwidth measurement mode and begins outputting digital data.Therefore, I set INT2_MAP register to 0x01( Map data ready interrupt onto INT2). When the sensor is in instant-on mode and there is no external impact(sensor is stationary) , there is no interrupt on INT2. I confirmed this by using oscilloscope. When I apply around 10g shock, sensor interrupts although the threshold is 30-40g. Is there any problem about my configurations ? or Is there a problem about instant-on threshold? Even small shock values, sensor interrupts regardless of instant-on threshold. I am also sure that sensor is in instant on mode. I confirmed it by looking at power consumption. 

Thank you.