jquery datepicker would not work

I have an @Html.edifor to show date of birth and I want to use jquery datepicker to show calendar. My scritp code is located in an external js file and proper reference to the file is on the view. I am also using bundle in app config.

 

here is my script

 

$(function ()

{

$("#DateOfBirth").datepicker({ dateFormat: "dd-MMM-yy", changeMonth: true, changeYear: true });

});

 

I am getting the following error. Jquery?v=gywVLk6VvVVR_J6-oRPIvBpBvXSXEW6ZffeMhgu--bE1:1 Uncaught TypeError: $(...).datepicker is not a function.

 

Can someone help me spot what is wrong.

 

Thank you!