datepicker in updatepanel

datepicker in updatepanel

hello,
 
I am using datepicker inside update panel  in asp.net 3.5.  I have created following date picker
$( ".datepicker" ).datepicker({ dateFormat: 'yy-mm-dd' , showOn: 'button' , buttonImage: '/Trap/Images/calendar.gif' , buttonImageOnly: true });
 
The problem is, when I submit the page, it loses the calendar image icon. I can no longer the see the calender icon. Please advice.