Datepicker not appearing only when a page is called within another page

Datepicker not appearing only when a page is called within another page

Bit of an odd one here that I can't understand.
I utilize DatePicker from the latest jquery on several ASP pages.
I am streamlining our site to have less direct page submissions which means the content is being called to a div by AJAX now.
 
If I open the pages directly datepicker is present and working, if I load the page into a div with AJAX Datepicker doesn't appear.
 
Thoughts?
I can include any code desired.
 
Here are the basics:
 
<!-- Setup Datepicker: this is included in my script.js and works perfectly on a direct page open-->
<script type="text/javascript">
<!--
  $(function() {
   $('input').filter('.datepicker').datepicker({
    changeMonth: true,
    changeYear: true,
    showOn: 'button',
    buttonImage: '/images/date.gif',
    buttonImageOnly: true
   });
  });
-->
</script>













Within any of my pages it is called with the following and it works perfectly when the page is opened directly but not when called dynamically:
<input type="text" name="txtworkdate" id="workdate" value="<% = workdate %>" style="width: 80px;" class="datepicker" />
 
TIA,
Jason