title: Magento Model source model - Call to a member function toOptionArray() on a non-object error
body: <p>I'm trying to set a source_model on a custom module in Magento.
  module is in local/Bitstream/Selfawb
  in system.xml I have this:</p>
  
  <pre><code>                        &lt;email_type translate="label"&gt;
                          &lt;label&gt;Email Type&lt;/label&gt;
                          &lt;frontend_type&gt;multiselect&lt;/frontend_type&gt;
                          &lt;source_model&gt;bitstream/source_emailType&lt;/source_model&gt;
                          &lt;sort_order&gt;3&lt;/sort_order&gt;
                          &lt;show_in_default&gt;1&lt;/show_in_default&gt;
                          &lt;show_in_website&gt;1&lt;/show_in_website&gt;
                          &lt;show_in_store&gt;1&lt;/show_in_store&gt;
                      &lt;/email_type&gt;
  </code></pre>
  
  <p>And EmailType.php is in /local/Bitstream/Selfawb/Model/EmailType.php with the folowing code:</p>
  
  <pre><code>class Bitstream_Selfawb_Model_Source_EmailType{
  
  public function toOptionArray(){
      return array(
          array('value'=&gt;'mobile', 'label'=&gt;Mage::helper('mailchimp')-&gt;__('MOBILE')),
      );
  }
  </code></pre>
  
  <p>}</p>
  
  <p>The problem is I get this error in browser: Fatal error: Call to a member function toOptionArray() on a non-object</p>
  
  <p>What am I doing wrong here?</p>