Ajax & getelementbyId - Problem

[dude]

ok hier nun der CODE:
1.) view.php
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<div>
<script type="text/javascript">

function display_data(id,type,gal) {

xmlhttp=GetXmlHttpObject();

if (xmlhttp==null) {
    
        alert ("Your browser does not support AJAX!");
        return;
    }

var url= "http://domain/data.php";
    url=url+"?type="+type+"&id="+id+"&gal="+gal;

xmlhttp.onreadystatechange=function() {
    
        if (xmlhttp.readyState==4 || xmlhttp.readyState=="complete") {
       
            document.getElementById('data_preview_ajax').innerHTML = xmlhttp.responseText;
        }
    }

xmlhttp.open("GET",url,true);
    xmlhttp.send(null);
}

function GetXmlHttpObject() {

var xmlhttp=null;
    try {
        // Firefox, Opera 8.0+, Safari
        xmlhttp=new XMLHttpRequest();
    }
    catch (e) {
        // Internet Explorer
        try {
            xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch (e) {
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
    }

return xmlhttp;
}

							function func\_img\_prev(val) {  

document.getElementById('img_preview_src').src=document.getElementById('img_prev_' + val).src;
document.getElementById('data_preview').innerHTML='<input type="hidden" name="pic_preview" value="' + val+ '">';

alert(document.getElementById("img_prev_" + val).src);

							};  
							  
							func\_img\_prev(1);  

</script>
<div id="data_preview_ajax" style="height:110px; width:260px; overflow: auto; float: left"></div>
<div id="img_preview" style="margin-left:280px; height:100px; width:150px;"><img id="img_preview_src" src="../img/leistungen_no_prev_small.jpg" height="100"></div>
div id="data_preview"></div>
</div>

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2.) data.php
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<div style="width:20px; height:95px; float:left; padding:5px 0 0 7px; margin:0 10px 0 0px; background-color:#c5d5fc"><b>01</b></div> <img id="img_prev_1" src="../images/galerie/gal_1/dat_46deefcb3ba260ea267ed404e0ec4d22.jpg" height="100" border="0" name="1" onclick="JavaScript:func_img_prev(1)"><p>