Datepicker does not take date second time inside the modal box

I have added a datepicker by using the following code :-

$("#txtChequeDate").datepicker({

dateFormat: 'dd/mm/yy' ,

changeMonth:true,

changeYear:true,

yearRange: '1965:*',

});

This datepicker field is inside a div to which i am calling as a modal box.

I am using default modal box for this purpose.

I am using Jquery v1.7.1 and mozilla firefox.

The datepicker works fine the first time the modal is opened and then the form submitted (after which the modal closes). However, if I click the button to open the modal a second time, datepicker doesn't work.