$.getJson callback function is not working

Question

I am calling a JSP by passing parameters which outputs a valid JSON as response, but still the $.getJson callback function is not getting fired. JSP page output is

 { "data": [ [ [ 1258185480000,4.39], 
               [ 1258186020000,4.31],
               [ 1258184940000,4.39],
               [ 1258183560000,4.39]  ] ] }

The URL points to the JSP page

My jquery code is

<script id="source" language="javascript" type="text/javascript">
$(function () {   
  alert("before");
  $.getJson(URL,function(json){
            alert("hello");
          var plot = $.plot($("#placeholder"), json.data, options);
    });

 alert("after");
});

Answer 1

The function is $.getJSON and not $.getJson

Answer 2

Also ensure with Firebug that you are getting valid JSON back from the server.