date picker

date picker

I have a date picker with id="datepicker" and I am trying to catch when the date is chaged with this code, but the change function is never activated.  What event do I need?  I have tried click.

< script type ="text/javascript">
$(document).ready( function () {

   $(
'#datepicker' ).datepicker().children().show();

   $(
'select[id$=datepicker]' ).change( function () {

$(

"input[id$=TextBox1]").val($("select[id$=datepicker] option:selected").val());

   });
});

</ script >