Hello everyone, This is part of my code, I don't know where my problem is, can you help me？

<arg name="use_gui" default="true" doc="Should the joint_state_publisher use a GUI for controlling joint states" />

<node name="joint_state_publisher_gui" pkg="joint_state_publisher_gui" type="joint_state_publisher_gui" />

<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" />

<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />

<node name="rviz" pkg="rviz" type="rviz" args="-d $(find mbot_description)/config/mbot.rviz" required="true" />