No link elements found in urdf file

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Hello. I am struggling with getting simple xacro macros to work. I have checked the other answers on this question but I can't get it to work. I'm using ROS1 Noetic distribution. My issue occurs when I try to create a link using a macro in a Xacro file, upon launching rviz I get the error: 'no link elements found in urdf file'. I have tried launching the same file without the macro and the link is made in rviz. Below is the code.

<?xml version="1.0" encoding="utf-8"?>

<robot name = quadruped xmlns:xacro="http://www.ros.org/wiki/xacro">

    <xacro:macro name = "link_shoulder" params= "name">
        <link name="caster_${name}">
        </link>
    </xacro:macro>

    <xacro:link_shoulder name="asd">
    </xacro:link_shoulder>
</robot>

Again if I remove the macro and simply use:

<?xml version="1.0" encoding="utf-8"?>

<robot name = quadruped xmlns:xacro="http://www.ros.org/wiki/xacro">
<link name="some_name">
        </link>
</robot>

It works just fine. The launch file I'm using is:

<launch>
  <arg
    name="model" />
  <param
    name="robot_description"
    textfile="$(find urdf_dummy)/urdf/base_link.xacro" />
  <node
    name="joint_state_publisher_gui"
    pkg="joint_state_publisher_gui"
    type="joint_state_publisher_gui" />
  <node
    name="robot_state_publisher"
    pkg="robot_state_publisher"
    type="robot_state_publisher" />
  <node
    name="rviz"
    pkg="rviz"
    type="rviz"
    />
</launch>