This robot has a joint named "steering_link" which is not in the gazebo model.

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Hey I have been following the Gazebo tutorial and tried to make my own robot. However, I got the error that says " This robot has a joint named "steering_link" which is not in the gazebo model."

The following is my URDF file:

<?xml version="1.0"?>

<robot name="scooter" xmlns:xacro="https://www.ros.org/wiki/xacro">

<xacro:include filename="$(find scooter)/urdf/properties.xacro"/>
<xacro:include filename="$(find scooter)/urdf/scooter.gazebo" />

<!-- base_link -->    
<link name="base_link"/>

<!-- steering_link -->

<link name="steering_link">
    <visual>
        <geometry>
            <cylinder radius="${thick_steering}" length="${steering_length}"/>
        </geometry>
        <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
        <material name='blue'/>
    </visual>

    <collision>
        <geometry>
            <cylinder radius="${thick_steering}" length="${steering_length}"/>
        </geometry>
        <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>           
    </collision>

    <mass value="${mass_steering_link}"/>
    <inertia ixx="${steering_ixx}" ixy="${steering_ixy}" ixz="${steering_ixz}" iyy="${steering_iyy}" iyz="${steering_iyz}" izz="${steering_izz}"/>
</link>

    <joint name="front_wheel_to_steering_joint" type="revolute">
        <parent link="base_link"/>
        <child link="steering_link"/>
        <origin xyz="-${(steering_length/2 * cos(alpha))} 0.0 ${(steering_length/2 * sin(alpha)) + rad_front_wheel}" rpy="0.0 -${pi/2 - alpha} 0.0"/>
        <limit lower="-${pi/4}" upper="${pi/4}" effort="0.0" velocity="0.0"/>
        <axis xyz="0 0 1"/>
    </joint>


<transmission name="tran1">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="steering_link">
    <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="steering_motor">
    <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
    <mechanicalReduction>1</mechanicalReduction>
    </actuator>
</transmission>

</robot>

Update: The problem was that I have used links instead of joints in transmission part