$.ajax success and error

$.ajax success and error

Hi. I'm relatively new to jquery. I was trying to do the authentication using JSON API's and if its a success it should start holding the session. If the JSON api doesn't retrieve any results, it should pop an alert showing "Not a User

Here is the script. I'm not sure what is missing. Its able to display "success loop" message but not the error alert
  2. $.ajax
  3. ({ 
  4.             type: 'GET', 
  5.               url: link,
  6.             dataType: "jsonp", 
  7.             success: function (data) 
  8.             { 
  9.            
  10.             $.session("sessionVariable",username);
  11.             //alert($.session("sessionVariable"));
  12.                 alert("success loop");
  13.                
  14.            },
  15.            
  16.           error: function () {
  17.         alert("not a user. Unable to login")
  18.       }
  19.            
  20.         });