document.write not working in ajax update panel

I have a problem rendering document.write() on a label which is there in ajax update panel. if i move the code out of the update panel everything works fine but not inside update panel.
Button click event i m writing code like below
Load.Text = String.Format("<script type='text/javascript'>document.write(new Date('{0:MMMM d, yyyy hh:mm:ss tt} UTC').toLocaleString());</script>", "2014-05-28 18:38:44.043")
When i click on a button the result should display in html. i can see the below code in page view source but its not rendering on the page.
<span id="MainContent_GTMLastStatusLoad" style="font-family:Arial,Helvetica Neue,Lucida Grande,Segoe UI,Helvetica,Verdana,sans-serif;font-size:11px;"><script type="text/javascript">document.write(new Date('2014-05-28 18:38:44.043 UTC').toLocaleString());</script></span>