title: Event observer not firing from custom module when coupon is applied on checkout page
body: <p>I want to do something after a coupon is applied during the checkout process.  I used the 'catalogrule_after_apply' event along with the corresponding function in Observer.php. The coupon is still being applied without hitting my observer method. I have other events firing, so invalid xml wouldn't be the case.  The issue might be the event i am using, but i cant find any other event that would yield the same effect.  Suggestions? </p>
  
  <p>etc/config.xml</p>
  
  <pre><code>&lt;config&gt;
         &lt;events&gt;
              &lt;catalogrule_after_apply&gt;
                  &lt;observers&gt;
                      &lt;promosource&gt;
                          &lt;type&gt;singleton&lt;/type&gt;
                          &lt;class&gt;promosource/observer&lt;/class&gt;
                          &lt;method&gt;addSourceIdToSessionFromCoupon&lt;/method&gt;
                      &lt;/promosource&gt;
                  &lt;/observers&gt;
              &lt;/catalogrule_after_apply&gt;
          &lt;/events&gt;
  &lt;/config&gt;
  </code></pre>
  
  <p>Helper/Observer.php</p>
  
  <pre><code>&lt;?php
  class Russ_Promosource_Model_Observer
  {
      public function __construct()
      {
      }
  
      public function addSourceIdToSessionFromCoupon($observer) {
  
                  die ('event observer worked');
      }
  
  }
  </code></pre>
  
  <p>Thank you in advance.</p>