问使xmlHTTPrequest不工作

EN

 function loadXMLDoc7(url)
        {
        if (window.XMLHttpRequest)
          {// code for IE7+, Firefox, Chrome, Opera, Safari
          xmlhttp=new XMLHttpRequest();
          }
        else
          {// code for IE6, IE5
          xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
          }
        xmlhttp.open("GET",url,false);
        xmlhttp.send(null);
        document.getElementById('newcomments').innerHTML=xmlhttp.responseText;
        }

    echo "<script type='text/javascript'>
    function auto2comments()
    { 
    var MyDiv1 = document.getElementById('uiuiui');";
    echo "loadXMLDoc7(MyDiv1.innerHTML)";
    echo "}";
    echo "setInterval(\"auto2comments()\",15000);</script>";
    }