dd_robot2.urdf help

edit

Hi I am reading "ROS ROBOTICS BY EXAMPLE SECOND EDITION " and I am stuck in chapter 2 , when it introduces the dd_robot2.urdf. What I am getting is the image blow

but the book has this instead:

I followed the book step by step and I cant figure out where I went wrong. Any help? Thank you!

EDIT1:

EDIT 2:

Launch File:

<launch>
   <!-- values passed by command line input -->     
   <arg name="model" />
   <arg name="gui" default="False" />

   <!-- set these parameters on Parameter Server -->
   <param name="robot_description" textfile="$(find ros_robotics)/urdf/$(arg model)" />
   <param name="use_gui" value="$(arg gui)"/>

   <!-- Start 3 nodes: joint_state_publisher, robot_state_publisher and rviz -->
   <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" />

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

   <node name="rviz" pkg="rviz" type="rviz" args="-d $(find ros_robotics)/urdf.rviz" required="true" />
   <!-- (required = "true") if rviz dies, entire roslaunch will be killed -->
</launch>

URDF File:

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

  <!-- Base Link -->
  <link name="base_link">
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
          <box size="0.5 0.5 0.25"/>
      </geometry>
    </visual>
  </link>

  <!-- Right Wheel -->
  <link name="right_wheel">
    <visual>
      <origin xyz="0 0 0" rpy="1.570795 0 0" />
      <geometry>
          <cylinder length="0.1" radius="0.2" />
      </geometry>
    </visual>
  </link>
  <joint name="joint_right_wheel" type="continuous">
    <parent link="base_link"/>
    <child link="right_wheel"/>
    <origin xyz="0 -0.30 0" rpy="0 0 0" /> 
    <axis xyz="0 1 0" />
  </joint>

  <!-- Left Wheel -->
  <link name="left_wheel">
    <visual>
      <origin xyz="0 0 0" rpy="1.570795 0 0" />
      <geometry>
          <cylinder length="0.1" radius="0.2" />
      </geometry>
    </visual>
  </link>
  <joint name="joint_left_wheel" type="continuous">
    <parent link="base_link"/>
    <child link="left_wheel"/>
    <origin xyz="0 0.30 0" rpy="0 0 0" /> 
    <axis xyz="0 1 0" />
  </joint>

</robot>

Command on terminal:

$ roslaunch ros_robotics ddrobot_rviz.launch model:=dd_robot2.urdf

Edit3: