Moveit tutorial with loading control for gazebo error

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Hi, everyone!

I'm trying to learn ROS by following the tutorials. And I'm trying to do the moveit tutorial with the panda arm. Everything works fine Rviz, I can plan and execute and everything. But when I launch the file demo_gazebo.launch, I receive this error

[ERROR] [1560572297.735318301, 0.334000000]: No joint given (namespace: /arm_position_controller)
[ERROR] [1560572297.735363567, 0.334000000]: Failed to initialize the controller
[ERROR] [1560572297.735423705, 0.334000000]: Initializing controller 'arm_position_controller' failed

Everything is generated, I didn't change a thing. Except that I use the generated gazebo file and change the path of demo_gazebo.launch and gazebo.launch to that file. Does anyone know what happen here? I'm extremely new to ROS. So pardon my ignorance. Thank you in advance!