title: ExtJS 4.2.1 Model - field defaultValue: undefined is not a function
body: <p>In my application i got e.g. two Models like this: </p>
  
  <pre><code>Ext.define('App.model.Translation', {
      extend: 'App.model.MRModel',
      requires: 'App.model.TranslationItem',
  
      fields: [
         ...
      ],...
  </code></pre>
  
  <p>and</p>
  
  <pre><code>Ext.define('App.model.administration.Station', {
      extend: 'App.model.MRModel',
      requires: [
          'App.model.Translation',
          'App.classes.proxy.ProxyNegotiator'            
      ],
  
      fields: [
          ...
      ],...
  </code></pre>
  
  <p>and in my Model Station i want to add a field with the default value of a new Translation like this:</p>
  
  <pre><code>Ext.define('App.model.administration.Station', {
      extend: 'App.model.MRModel',
      requires: [
          'App.model.Translation',
          'App.classes.proxy.ProxyNegotiator'        
      ],
  
      fields: [
          { name: 'Id', type: 'int', convert: null },
          {
              name: 'Name',
              type: 'auto',
              convert: function(value) {
                  ...
              },
              defaultValue: new App.model.Translation()
          },
  </code></pre>
  
  <p>though when i am inserting this line with the default Value i get the following error: <code>Uncaught TypeError: undefined is not a function</code> 
  It seems that the Translation class is not loaded jet.. I dont understnand this cuz i added the class to the requires array...</p>
  
  <p>Please help.</p>