[jQuery] onChange event and ptTimeSelect

[grep]

I'm fairly new to jQuery and javascript - I'm also sure I'm missing a
simple concept here but, I can't seem to be able to google myself an
answer.

Situation:
I am using the ptTimeSelect plugin 
http://pttimeselect.sourceforge.net/example/index.html.

Code-Snippet:
<script src="/jquery.js"              type="text/javascript"
language="JavaScript"></script>
<script src="/dimensions.js"          type="text/javascript"
language="JavaScript"></script>
<script src="/jquery.ptTimeSelect.js" type="text/javascript"
language="JavaScript"></script>

<script type="text/javascript">
  $(document).ready(function(){
    $("[EMAIL PROTECTED]").ptTimeSelect();
  });

  $(document).ready(function(){
    $("[EMAIL PROTECTED]").change( function() {
      alert("SpooN");
    });
  });
</script>

Question:
The onChange handler fires if I manually edit the input field in
question. But the onChange handler doesn't fire if the ptTimeSelect
modifies the field. What do I need to do to get my function to fire
when the ptTimeSelect modifies a field?

Christian