From date To date Validation not working

See more:

C#

jQuery

I have the below code for start date end date validation. But the code is not working.
Dates below the from_date textbox can be selected using to_date textbox.
Please help.

$(document).ready(function(){
    $("#txtFromDate").datepicker({
        numberOfMonths: 2,
        onSelect: function(selected) {
          $("#txtToDate").datepicker("option","minDate", selected)
        }
    });
    $("#txtToDate").datepicker({
        numberOfMonths: 2,
        onSelect: function(selected) {
           $("#txtFromDate").datepicker("option","maxDate", selected)
        }
    });
});