Java Script Probleme mit Fancybox und XMLHttpRequest

<script type="text/javascript" src="class/fancybox/jquery-1.2.3.pack.js"></script>  
<script type="text/javascript" src="class/fancybox/jquery.fancybox-1.0.0.js"></script>  
<script type="text/javascript" src="class/fancybox/jquery.pngFix.pack.js"></script>  
<link rel="stylesheet" href="class/fancybox/fancy.css" type="text/css" media="screen">  

<script type="text/javascript">  
   $(document).ready(function() {
   $("p#Bild1 a").fancybox();  

      $("p#lightmerkliste a").fancybox();  
     
      $("a#lightmerkliste").fancybox({  
           'zoomSpeedIn':10,  
           'zoomSpeedOut':10  
       });
              
    });

function sendRequest(cli) {
        var req;
        try {
                req = window.XMLHttpRequest?new XMLHttpRequest():
                new ActiveXObject("Microsoft.XMLHTTP");  
                document.getElementById('myContent').innerHTML = '<img src="img/preloader.gif"><br />ULL Live-Check f&uuml;r Nummer: '+cli+'<br /> in Bearbeitung...';  
        } catch (e) {
                //Kein AJAX Support
        }
 
        req.onreadystatechange = function() {
                if ((req.readyState == 4) && (req.status == 200)) {
                        document.getElementById('myContent').innerHTML = req.responseText;  
                }
        };
        var id = cli;
        req.open('post', 'xipindex.php');  
        req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');  
        req.send('cli='+ id);  
}