How to disable and enable a dropdownlist in Jquerymobile

How to disable and enable a dropdownlist in Jquerymobile

Hello, I'm kinda new to Jquery mobile. I building a mobile app with asp.net mvc4 and using jquery moblie in the UI.
 
I have two dropdownlists and I want enable or disable one based on the selection of the previous one. How do I go about it.

I tried this earlier but it did not work.

  1. <script type="text/javascript">
  2.     $(document).ready(function(){

  4.         

  6.         $("SelectedActionForUser").change(function () {
  7.             
  8.             
  9.             if ($(this).val() == "3") {
  10.                
  11.                 
  12.                 $("#SelectedEmployee").prop('disabled', false);
  13.                 
  14.                
  15.             }
  16.             else {
  17.                 $("#SelectedEmployee").prop('disabled', true);

  19.             }
  20.         });

  22.        
  23.     });

  25.     
  26. </script>