title: Error on run: Property validation failure: [Value of property {/Targets/0/Values} does not match type {Array}]
body: <p>This CF is being created in <strong>YAML</strong> not JSON.</p>
  
  <p>I am building Systems Manager Maintenance Windows, Targets and Tasks through Cloudformation.</p>
  
  <p>When creating the stack, the Resources: MaintenanceWindow: section complete successfully. It's the next section (below) that is failing. Not sure about the last section as we never get there.</p>
  
  <p>Here is the location for the full template: <a href="https://pastebin.com/DNEkLPGS" rel="noreferrer">https://pastebin.com/DNEkLPGS</a></p>
  
  <p>I have tried using validators and everything (YAML and the CloudFormation Validators) and everything comes back as good.</p>
  
  <p>Here is the section giving errors:</p>
  
  <pre><code>Parameters:
    MaintenanceTargetName:
      Description: Maintenace Target Name (No Spaces)
      Type: String
    MaintenanceTargetDescription:
      Description: Sample - UAT Servers
      Type: String
      MaxLength: '128'
    MaintenanceTargetTarget:
      Description: Tag Key should equal 'AgentUpdate'
      Type: String
      Default: tag:AgentUpdate
    MaintenaneTargetKeyValue:
      Description: True or False
      Type: String
      Default: True
      AllowedValues:
        - True
        - False
  
  Resources:
    MaintenanceWindowTarget:
      Type: 'AWS::SSM::MaintenanceWindowTarget'
      Properties:
        WindowId: !Ref MaintenanceWindow
        ResourceType: INSTANCE
        Targets:
          - Key: !Ref MaintenanceTargetTarget
            Values: !Ref MaintenaneTargetKeyValue
        Name: !Ref MaintenanceTargetName
        Description: !Ref MaintenanceTargetDescription
  </code></pre>
  
  <p>Running the template gives the following error:</p>
  
  <p>MaintenanceWindowTarget |  <strong>CREATE_FAILED</strong> | Property validation failure: [Value of property {/Targets/0/Values} does not match type {Array}]</p>