Jetbot_follow_me.usd not working for me because of camera

Hello,

I followed this “Jetbot Sample Applications — ISAAC 2021.1 documentation” and trying to do " Jetbot Autonomously Following Objects in Simulation", however, the camera is completely black screen on the Isaac Sight so that I cannot see any detection results.

Here what I am trying to say:

Any help or idea would be great !!

Additionally,

when I run " bazel run apps/jetbot:jetbot_jupyter_notebook", there is a notebook, it is OK. However, there is line in one of the following cells which is
“”"
(inference_component.config.model_file_path = “external/jetbot_ball_detection_resnet_model/jetbot_ball_detection_resnet18.etlt”)
“”"

and I couldn’t find any app for creating “jetbot_ball_detection_resnet18.etlt”

Little help would be great !!!