datepicker function enhancement (like date range) not working

datepicker function enhancement (like date range) not working

Dear Sir

refer

click on  Last Date

Date picker is working
but
I am not getting result  from setting 

  1.  $( "#lastdt" ).datepicker({ minDate: -20, maxDate: "+1M +10D" });// not working//

Minimum
maximum Date


  1. <script>
  2.  
  3.   $( function() { $( ".datepicker" ).datepicker();

  4.  $( ".datepicker" ).datepicker( "option", "dateFormat", "dd-mm-yy" );
  5.  $( "#lastdt" ).datepicker({ minDate: -20, maxDate: "+1M +10D" });// not working//
  6.   $( "#lastdt" ).datepicker({ // not working//
  7.       showOn: "button",
  8.       buttonImage: "images/calendar.gif",
  9.       buttonImageOnly: true,
  10.       buttonText: "Select date"
  11.     });
  12.  
  13.     $( "#items_table    [id*='delivery']" ).datepicker({ minDate: -30, maxDate: "+2M +1D" } );;

  14.   } );
  15.   </script>