AJAX Not Loading XML Value

I am still getting used to things like ajax and have a problem. I am creating a PBBG, a game made out of HTML, CSS, JS, ect. I have some code that will repace the content of some cells of the table with the values of some XML tags. It only is changing one box for now.

Basicly I want it to open the XML file, get "Archer" from the name tag, and place it in the th tag. But right now it only says "undefined". I figured out that that problem is with line 12 of my JS but I can't figure out how to fix it. Any help is apreiciated, thanks!

I will leave a simplified vertion of the code here. (Simplifed being all the parts being used left.)

XML
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE unit SYSTEM "unit.dtd">
<unit>
<name>Archer</name>
</unit>

HTML
<table>
<tr>
<th id="Name" colspan="2">

</th>
</tr>
</table>

JS
function Archer()
{
if (window.XMLHttpRequest)
{xmlhttp=new XMLHttpRequest();}
else
{xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
txt="";
x=xmlhttp.responseXML.documentElement.getElementsByTagName('name');
txt=x.data;
document.getElementById('name').innerHTML=txt;
}
}
xmlhttp.open("GET","Units/Archer.xml",true);
xmlhttp.send();
}
I have it set to onload="Archer()"

I see some errors.

id naming error:

First, you have "Name" with capital "N" in your th tag:
<th id="Name" colspan="2">

But in your JavaScript code, you are trying to find 'name' in lowercase.

document.getElementById('name').innerHTML = txt;

This will cause an error (can't set null value to innerHTML), because there is no id with "name".

Fix your th tag and make the id lowercase:
<th id="name" colspan="2">

XML errors:

You aren't properly accessing your 'name' node, as you need an index value(like [0]), and also you aren't accessing the value in the child of that node by using nodeValue.

Replace these lines:
txt="";
x=xmlhttp.responseXML.documentElement.getElementsByTagName('name');
txt=x.data;
document.getElementById('name').innerHTML=txt;;
With this:
var txt = "";
var x = xmlhttp.responseXML.documentElement.getElementsByTagName('name')[0];
var y = x.childNodes[0];
txt = y.nodeValue;

document.getElementById('name').innerHTML = txt;