Code funktioniert plötzlich nicht mehr

<script type="text/javascript">
//Name des Gästebuches
var nameOfGB = 'G.ae.stebuch';

//URL des Zurück-Button
var back = 'http://img.webme.com/pic/k/klein-paris/playicon1.png';

//URL des Weiterbutton
var next = 'http://img.webme.com/pic/k/klein-paris/playicon2.png';


//Ab hier nichts mehr ändern
var i;
var done = false;
var temp = window.location.href.toLowerCase();

if(temp.indexOf('/' + nameOfGB.toLowerCase()) != -1)
{
var allTDs = document.getElementsByTagName('td');

for(i = 0; (i < allTDs.length) && (!done); i++)
{
if(allTDs[i].width == '33%' )
{
if((allTDs[i].align == 'left') && (allTDs[i + 1].align == 'center') && (allTDs[i + 2].align == 'right'))
{
if((allTDs[i].firstChild.firstChild.nodeValue.toLowerCase().indexOf('zurück') != -1) && (allTDs[i + 2].firstChild.firstChild.nodeValue.toLowerCase().indexOf('weiter') != -1))
{
temp = document.createElement('img');
temp.src = back;
temp.alt = 'back';

allTDs[i].firstChild.removeChild(allTDs[i].firstChild.firstChild);
allTDs[i].firstChild.appendChild(temp);

temp = document.createElement('img');
temp.src = next;
temp.alt = 'next';

allTDs[i + 2].firstChild.removeChild(allTDs[i + 2].firstChild.firstChild);
allTDs[i + 2].firstChild.appendChild(temp);

done = true;
}
}
}
}
}
</script>