Facebook Messenger Nested Persistent Menu Error

I'm trying to add a persistent menu to my chatbot. Facebook has a limit of 3 buttons but you can have a nested button with a maximum of 5 buttons.

This is the error I get when I run my code

response body error

type: 'OAuthException',

Error: { message: '(#100) Invalid keys "call_to_actions" were found in param "call_to_actions[0]".', code: 100}

Here is my code:

function addPersistentMenu(){
  request({
    url: "https://graph.facebook.com/v2.6/me/thread_settings",
    qs: {access_token: token},
    method: "POST",
    json:{
      setting_type : "call_to_actions",
      thread_state : "existing_thread",
      call_to_actions : [
        {
          type: "nested",
          title: "Menu Item One",
          call_to_actions: [
            {
              type: "postback",
              title: "Nested Item One",
              payload: "NESTED_ONE"
            },
            {
              type: "postback",
              title: "Nested Item Two",
              payload: "NESTED_TWO"
            }
           ]
        },
        {
          type: "postback",
          title: "Menu Item Two",
          payload: "TWO"
        },
        {
          type: "postback",
          title: "Menu Item Three",
          payload: "THREE"
        }
      ]
    }
  }, function(error, response, body) {
      if(error){
        console.log('sending error')
        console.log('Error sending messages: ', error)
      }else if(response.body.error){
        console.log('response body error')
        console.log('Error: ', response.body.error)
      }
   });
}

When I remove the nested button, the persistent menu appears so I'm not sure what the error is. My code is pretty similar to the sample posted by facebook in their persistent menu doc. I'm programing using node.js, hosted on heroku and I modeled my menu function after the code found here.

Question: How do I add my nested persistent menu and what does this error mean?

via Mimi.O