unable to bind view to store size

How to bind to store size?

After store load, view is not updated.

I use formula to achieve this, because adding braces in bind descriptor causes errors:

Code:

Ext.define('cas.view.stationlist.StationListModel', {
  extend: 'Ext.app.ViewModel',
  alias: 'viewmodel.stationlist',
  data: {
    name: 'stations list model',
    callCounter:0
  },
  stores: {
    stations: {
      source: 'Stations',
      autoLoad: true
    }
  },
  formulas: {


    numStations: function (get) {
      var count = get('stations').getCount();
      var str = "Station (" + count + ")";
      this.set("callCounter", this.get('callCounter')+1)
      return str + " / call counter: "+this.get('callCounter');


    }
  }


});

WORKING fiddle:

http://ift.tt/1ifUu3l

(there are multiple files)

There is numStations formula that additionaly shows number of function call.

Expected bind results after store load:
Items List (total: 10) / call counter: 2

Current results:

Items List (total: 0) / call counter: 1