从一个JSON更新多个div - 简单示例不起作用

I have a webservice getupdate.php with the following code:

<?php
    $aReturn['status'] = "This is the last update";
    $aReturn['lastupdate'] = "2 minutes ago";
    echo json_encode($aReturn);
?>

It produces the expected output: {"status":"This is the last update","lastupdate":"2 minutes ago"}

I'm trying to update to div's every 5 sec with this:

<script src='http://code.jquery.com/jquery-latest.js'></script> 
<script type="text/javascript">

    $.ajaxSetup ({  
        cache: false  
    });  

    setInterval(function(){
        $.getJSON('getstatus.php', function(data) {
        $('div#status').html(data.status);
        $('div#lastupdate').html(data.lastupdate);
            }
        });
    }, 5000);

</script>


<div id="status">status</div>
<div id="lastupdate">lastupdate</div>

But for some - most likely very simple reason - my two div's are not updated. Can anyone tell my what I'm doing wrong here?