title: jQuery AJAX request is not a function
body: <p>I need a second pair of eyes on this as cannot see why it's returning:</p>
  
  <pre><code>$("#message").removeClass().addClass(data.error === true ? "error" : "success").html(data.msg).show is not a function
  </code></pre>
  
  <p>My code is as follows:</p>
  
  <pre><code>$.ajax({
          type : 'POST',
          url : 'postcode-lookup.php',
          dataType : 'json',
          data: {
              postcode : $('#postcode').val()
          },
          success : function(data){
              $('#waiting').hide(500);
              $('#message').removeClass().addClass((data.error === true) ? 'error' : 'success').text(data.msg).show(500);
              if (data.error === true)
                  $('#restricted_locator').show(500);
          },
          error : function(XMLHttpRequest, textStatus, errorThrown) {
              $('#waiting').hide(500);
              $('#message').removeClass().addClass('error').text('There was an error.').show(500);
              $('#restricted_locator').show(500);
          }
      });
  </code></pre>