joint_state_publisher won't move Rviz robot model

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Hello, I'm a total beginner in ROS. I have written a basic URDF of 2 links and 1 joint and try to simulate on Rviz.

After running roslaunch robot_description rviz.launch, rviz appears as usual with joint state publisher window, after adding Robot Model, when I change the value on joint state publisher, the joint link won't move.

May I know what I have done wrong? Thank you.

Code Here:

<?xml version="1.0"?>
<robot name="robot">

  <material name = "blue">
    <color rgba="0 0 0.8 1"/>
  </material>

  <material name = "white">
    <color rgba="1 1 1 1"/>
  </material>

  <link name="base">
    <visual>
      <geometry>
        <cylinder length="0.055" radius="0.055"/>
      </geometry>
      <material name="blue"/>
    </visual>
  </link>

  <link name="body">
    <visual>
      <geometry>
        <box size="0.06 0.06 0.084"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="white"/>
    </visual>
  </link>

  <joint name="base_body" type="continuous">
    <parent link="base"/>
    <child link="body"/>
    <axis xyz="0 0 1"/>
    <origin xyz="0 0 0"/>
  </joint>

</robot>