title: Zend Form Custom Filter Class not found
body: <p>My Custom Zend Form Filter Classes are not being loaded.</p>
  
  <p>The Custom Filter Class name is: <strong>SF_Filter_AlnumDashes</strong> and it resides into:
  library/SF/Filter/AlnumDashes.php.</p>
  
  <p>I have configured autoloading for the "SF_" namespace into application.ini:</p>
  
  <pre><code>autoloadernamespaces[] = "SF_"
  </code></pre>
  
  <p>But when I try to load the Class during Zend Form creation I get error that the class coudn't be found:
  <strong>Fatal error: Class 'AlnumDashesUnderscore' not found in...</strong></p>
  
  <p>Here is the code that is causing the error in the Zend Form class:</p>
  
  <pre><code>class Admin_Form_Product_Generalinfo extends SF_Form_Abstract {
  
      public function init() {
  
          //set ID Attribute on the form element
          $this-&gt;setAttrib('id', 'product_general_info');
  
          $elementPrefixPaths = array(
                  array(
                      array(
                          'prefix' =&gt; 'SF_Filter', 
                          'path' =&gt; 'SF/Filter/', // 'application/validators' in your case
                          'type' =&gt; 'filter',
                      )
                  )
              ); 
          $this-&gt;addElementPrefixPaths($elementPrefixPaths);
  
      $this-&gt;addElement('text', 'title', array(
  
              'filters' =&gt; array('StringTrim', 'StripTags'),
              'validators' =&gt; array(
          array('StringLength', true, array(2, 250)),
              ),
              'required' =&gt; true,
              'label' =&gt; 'Title',
              'attribs' =&gt; array(
                  'id' =&gt; 'title',
                  'class' =&gt; 'inputbox'
               )
  
      ));
  
          $this-&gt;getElement('title')-&gt;addFilter(array(new AlnumDashesUnderscore(), array(1)));
  </code></pre>
  
  <p>}</p>
  
  <p>I have other classes into "SF_" Namespace that get load successfully, calling them from Controllers with no problem.</p>