Datepicker and PHP

Datepicker and PHP

I am just starting to learn web programming and am trying to use datepicker in a simple php application.

The code is -
<!DOCTYPE html>
<html>
<head>
  <link type="text/css" href="/var/www/html/development-bundle/themes/base/ui.all.css" rel="stylesheet" />
  <script type="text/javascript" src="/var/www/development-bundle/jquery-1.3.2.js"></script>
  <script type="text/javascript" src="/var/www/development-bundle/ui/ui.core.js"></script>
  <script type="text/javascript" src="/var/www/development-bundle/ui/ui.datepicker.js"></script>
  <script type="text/javascript">
  $(document).ready(function(){
    $("#datepicker").datepicker()
}
);
 </script>
</head>
<body style="font-size:62.5%;">
 
<form method=post action="dateformat.php">
<input type='text' id='datepicker' name='thedate' class="date-pick" />
</form>
</body>
</html>

When i type in the URL, I see a text field. But when I click on it, no calendar opens up.
Thanks