how to get the depth value of a 2d pixel coordinate from RGB image

[Benxiaogu]

I need to get the 3d coordinate from a 2d coordinate from RGB image,
I tried the code from exampleTransformPoint2DTo3D.py
pos3d_color = device.calibration.convert_2d_to_3d(pixels, rgb_depth, K4A_CALIBRATION_TYPE_COLOR, K4A_CALIBRATION_TYPE_COLOR)
pos3d_depth = device.calibration.convert_2d_to_3d(pixels, rgb_depth, K4A_CALIBRATION_TYPE_COLOR, K4A_CALIBRATION_TYPE_DEPTH)

It cannot get the proper the value.
How do I get the proper 3d coordinate?
Thank you for your help