Data is null after AJAX request

Data is null after AJAX request

Hello,

I really don't understand why I am getting this error (parsererror TypeError: data is null [object XMLHttpRequest]) after making the following AJAX request:
  1.     var base_url = $('span#base_url').text();
        var model_url = "index.php/status/get_xml/"

        $.ajax({
            type: "POST",
            url: base_url + model_url,
            dataType: "xml",
            data: "{}",
            success: function parseXml(xml){
              //find every Tutorial and print the author
              $(xml).find("Tutorial").each(function()
              {
                $("#output").append($(this).attr("author") + "<br />");
              });
            },
            error: function(xmlhttp, status, error){$("#output").append(status+' '+error+' '+xmlhttp)}
        });















I can see I am receiving the XML by looking at the response (200) in Firebug:
  1. <?xml version="1.0" encoding="utf-8" ?> <RecentTutorials>  <Tutorial author="The Reddest">  <Title>Silverlight and the Netflix API</Title>  <Categories>  <Category>Tutorials</Category>  <Category>Silverlight 2.0</Category>  <Category>Silverlight</Category>  <Category>C#</Category>  <Category>XAML</Category>  </Categories>  <Date>1/13/2009</Date>  </Tutorial> </RecentTutorials>
So I am wondering why the .ajax function has an error, and yet the XML is being returned? Is this obvious to you?

Thanks,
Stephen