Contact Sensor Reading Problem: can not get the right data from contact sensor

Hey everyone:

I’m trying to acquire the contact sensor data from Isaac sim.
First I add the sensor in isaac sim gui as the following:

Then I write the code in my
The followings are my code:

from omni.isaac.sensor import _sensor
self._cs = _sensor.acquire_contact_sensor_interface()
sensor_data = self._cs.get_sensor_readings("/World/final6_only_hand/__6_2/__6_2/Contact_Sensor")

and the output is:
and I also tried the function: get_contact_sensor_raw_data but not work.
So how can I get the data from the contact sensor?

Thanks in advance!