error when using CustomMsg

[niuwenju]

SysCommand.publish - Unknown message class 'Livox/CustomMsg'
UnityEngine.Debug:LogError (object)
Unity.Robotics.ROSTCPConnector.ROSConnection:ReceiveSysCommand (string,string) (at C:/Users/niuwj.DIGITALCHINA/Desktop/ros_unity/ROS-TCP-Connector/com.unity.robotics.ros-tcp-connector/Runtime/TcpConnector/ROSConnection.cs:680)
Unity.Robotics.ROSTCPConnector.ROSConnection:Update () (at C:/Users/niuwj.DIGITALCHINA/Desktop/ros_unity/ROS-TCP-Connector/com.unity.robotics.ros-tcp-connector/Runtime/TcpConnector/ROSConnection.cs:587)

Not registered to publish topic '/livox/lidar'! Valid publish topics are: dict_keys([])
UnityEngine.Debug:LogError (object)
Unity.Robotics.ROSTCPConnector.ROSConnection:ReceiveSysCommand (string,string) (at C:/Users/niuwj.DIGITALCHINA/Desktop/ros_unity/ROS-TCP-Connector/com.unity.robotics.ros-tcp-connector/Runtime/TcpConnector/ROSConnection.cs:680)
Unity.Robotics.ROSTCPConnector.ROSConnection:Update () (at C:/Users/niuwj.DIGITALCHINA/Desktop/ros_unity/ROS-TCP-Connector/com.unity.robotics.ros-tcp-connector/Runtime/TcpConnector/ROSConnection.cs:587)