A quick question on data returned by jquery.ajax() call (EDITED)

Answer 1

Try defining your callback inline like this:

success: function createTaskListTable(data, textStatus, xhr) {
  console.dir(data, textStatus, xhr);
}

If data is indeed being returned as null, you might get some insight from the other fields, especially xhr.

Note that error callbacks get called with (xhr, textStatus, errorThrown).

Answer 2

See my comment. If you're using IE, GET AJAX requests are cached. jQuery can solve this for you by adding a random querystring variable to the request. Simply change your AJAX call to this:

$.ajax({
    type: 'GET',
    url: servicesUrl + "/" + ID + "/tasks",
    cache: false,
    dataType: "xml",
    success : createTaskListTable
});

That will add the random querystring automatically, thus preventing the browser from caching the request.