I don't know if I'm having a syntax error but the compiler is giving me

TypeError: 'undefined' is not an object (evaluating 'xmlDoc.getElementsByTagName("icon")[i].childNodes')

Its me giving me this problem when im parsing the XML from my server, my actual javascript code is like this

var xmlDoc = Obj.responseXML;
var count = 0;
if(xmlDoc){
    while(count <= xmlDoc.getElementsByTagName("item").length){
    document.getElementById("flow").innerHTML += "<div class='item'><img class='content' src='" + xmlDoc.getElementsByTagName("icon")[i].childNodes[0].nodeValue.replace(/\s+$/g,' ') +"' /></div>";
    count++;
    }
       }else{
           alert("Unable to parse!");
       }

and my XML goes like this.

<feed>
<item>
<title>Given Title</title>
<icon>
http://i178.photobucket.com/albums/w255/ace003_album/Logo-ETC-RGB-e1353503652739.jpg
</icon>
</item>
<item>...</item>
<item>...</item>
<item>...</item>
<item>...</item>
<item>...</item>
<item>...</item>
</feed>

i just want to parse the image link and to show it.