php+javascript (nefunguje)

/* =================================== doba nepritomnosti =================================== */ 
               $time_o = time()-30;
               $off_time = $join_db->query("SELECT u.nick 
                                            FROM users u
                                            LEFT JOIN online o on u.nick = o.nick 
                                            where o.nemluvil < '$time_o'
                                            ");
               if($off_time->num_rows > 0){
               $kick = $off_time->fetch_array();
               echo '<script type="text/javascript" language="javascript">parent.parent.location.href = "../?mag=#byl_jsi_kicknut";</script>';
               $join_db->query("DELETE FROM online WHERE nick='".$kick[0]."' AND r_id='".$_GET['rid']."'");
               }
/* ================================== !doba nepritomnosti! ================================== */  

function ajaxFunction()
{
    var xmlHttp;
    try {
        xmlHttp=new XMLHttpRequest();  
    }
      
    catch (e) {
        try {
            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch (e) {
            try {
                xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
            }
            catch (e) {
                alert("Nepodporuje AJAX");
                return false;
            }   
        }  
    }
    xmlHttp.onreadystatechange=function() {
        if(xmlHttp.readyState==4) {
        if (xmlHttp.status == 200) {
            var body = document.getElementsByTagName('body')[0];
            body.innerHTML = xmlHttp.responseText;
        }
        }
    }
    xmlHttp.open("POST",location.href,true); //php subor
    xmlHttp.send(null); 
  
}

function runTimer() {
    window.setInterval("ajaxFunction()", 5000);    //interval refreshu... 1000 = 1 sekunda
}