bagfile player problem

[agn-7]

I have a Lidar bagfile (hdl_400.bag)

When I run the following line, I dealing with this error:

~/catkin_ws/src/Didi_Challenge_2017_ROS/ros_script$ ./bag_player --file_path /home/user/<file-path>/hdl_400.bag

Error:

No messages to play on specified topics.  Exiting.
================================================================================REQUIRED process [bag_player-2] has died!
process has finished cleanly
log file: /home/agn/.ros/log/0464699e-c14d-11e8-ba55-dc5360059dc1/bag_player-2*.log
Initiating shutdown!
================================================================================

Another question is that, what is the difference between using rosbag play hdl_400.bag and using rosbagplay sh file?

[mumu999701]

when I run object_tracker --car
the error are lists:
object_tracker:command not find