I am using this code to set the default date of the datepicker to 7 days from today but it's not working and I am getting the datepicker blank.

what's wrong with the code please?

2.     <script type="text/javascript">
3.         $(function ()
4.         {
5.             $("#dateClosingDate").datepicker({ dateFormat: "dd-mm-yy",
6.             numberOfMonths: 2,
7.             changeMonth: true,
8.             changeYear: true,
9.             minDate: +1,
10.             maxDate: "+90D",
11.             setDate: 1,
12.             showOn: "button",
13.             buttonImage: "http://www.mywebsite.com/images/calendar.gif",
14.             buttonImageOnly: false })
15.         
16.             $("#dateClosingDate").datepicker( "option", "defaultDate", +7 );
17.         });