Cannot get Ember action to bubble

I have spent a lot of time trying to implement what ought to be a simple thing in Ember: bubbling an action from a component to the application controller. The docs say that in order to propogate an action then all I need to do is declare the action when I declare the template:

{{#if isLoggedIn}}
  {{menu-bar authenticate="authenticate"}}
{{/if}}

...and then send the action from the component (which is nested in the login route):

authenticate: function() {
  //code omitted for brevity
  this.sendAction();
}

...which should be received by the application controller:

  user: Ember.inject.service(),
  isLoggedIn: false,
  actions: {
    authenticate: function(){
      console.log('authenticated!');
      this.set('isLoggedIn', this.get('user').isLoggedIn());
    }
  }

but it isn't. And I'm wasting a lot of time trying to work out why.

I'm sure it's really obvious but if someone can tell me what I'm doing wrong I would greatly appreciate it.