custom robot not moving diff drive plugin

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Hello,

I am trying to simulate a custom robot. I am using ROS Noetic. Please find my gazebo file where I have added the plugin and my urdf file as well

<?xml version="1.0"?>
<robot name="rseries_bot" xmlns:xacro="http://ros.org/wiki/xacro">
  <xacro:include filename="$(find multibot_simulation)/urdf/rseries_bot.gazebo.xacro"/>

  <!-- ****************** ROBOT CONSTANTS *******************************  -->
  <xacro:property name="base_width" value="0.42"/>
  <xacro:property name="base_length" value="0.40"/>
  <xacro:property name="base_height" value="0.20"/>
  <xacro:property name="wheel_radius" value="0.0825"/>
  <xacro:property name="wheel_width" value="0.05"/>
  <xacro:property name="wheel_ygap" value="0.15"/>
  <xacro:property name="wheel_zoff" value="0.0"/>
  <xacro:property name="wheel_xoff" value="0.0"/>
  <xacro:property name="caster_xoff" value="0.217"/>
  <xacro:macro name="box_inertia" params="m w h d">
    <inertial>
      <origin xyz="0 0 0" rpy="${pi/2} 0 ${pi/2}"/>
      <mass value="${m}"/>
      <inertia ixx="${(m/12) * (h*h + d*d)}" ixy="0.0" ixz="0.0" iyy="${(m/12) * (w*w + d*d)}" iyz="0.0" izz="${(m/12) * (w*w +h*h)}"/>
    </inertial>
  </xacro:macro>

  <xacro:macro name="cylinder_inertia" params="m r h">
    <inertial>
      <origin xyz="0 0 0" rpy="${pi/2} 0 0" />
      <mass value="${m}"/>
      <inertia ixx="${(m/12) * (3*r*r + h*h)}" ixy = "0" ixz = "0" iyy="${(m/12) * (3*r*r + h*h)}" iyz = "0" izz="${(m/2) * (r*r)}"/>
    </inertial>
  </xacro:macro>

  <xacro:macro name="sphere_inertia" params="m r">
    <inertial>
      <mass value="${m}"/>
      <inertia ixx="${(2/5) * m * (r*r)}" ixy="0.0" ixz="0.0" iyy="${(2/5) * m * (r*r)}" iyz="0.0" izz="${(2/5) * m * (r*r)}"/>
    </inertial>
  </xacro:macro>

  <!-- ********************** ROBOT BASE *********************************  -->
  <link name="base_link">
    <visual>
      <origin xyz="0.0 0.0 0.08" rpy="0 0 0"/>
      <geometry>
        <mesh filename="package://multibot_simulation/mesh/robochef_body_final.stl" scale="0.0015 0.0015 0.0015"/>
      </geometry>
      <color rgba="${0/255} ${0/255} ${255/255} 1.0"/>
    </visual>

    <collision>
      <geometry>
        <box size="${base_length} ${base_width} ${base_height}"/>
      </geometry>
    </collision>

    <xacro:box_inertia m="20.0" w="${base_width}" d="${base_length}" h="${base_height}"/> 

  </link>

  <!-- *********************** DRIVE WHEELS ******************************  -->
  <link name="left_wheel_link">
    <visual>
      <origin xyz="0 0 0" rpy="1.5707963267949 0 0"/>
      <geometry>
        <mesh filename="package://multibot_simulation/mesh/wheel.stl" scale="0.0013 0.0013 0.0013"/>
      </geometry>
      <material name="White">
        <color rgba="${255/255} ${255/255} ${255/255} 1.0"/>
      </material>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="${pi/2} 0 0"/>
        <geometry>
          <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
        </geometry>
    </collision>

    <xacro:cylinder_inertia m="5.5" r="${wheel_radius}" h="${wheel_width}"/>

    </link>

    <joint name="left_wheel_joint" type="revolute">
      <parent link="base_link"/>
      <child link="left_wheel_link"/>
      <origin xyz="0.0 0.19 0.0" rpy="0 0 ...