IE9 behavior issue with onchange?

I'm trying to change the selection of one SELECT form based on what the user clicks in another SELECT form.  All the major browsers work as expected except IE9.  Before I reach this code I populate responseText by using PHP.

Code:

if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
var ajaxupdate = document.getElementById('region');
window.alert(xmlhttp.responseText);
ajaxupdate.value = xmlhttp.responseText;
}

The alert gives me the correct data in Chrome/Firefox/Safari but it's empty in IE9.  I'm using this javascript function to respond to the change:

Code:

onchange="showData(this.options[this.selectedIndex].value);"

Any ideas how to get this to work in IE9?

EDIT: Sorry for the edits.  I had to clarify my issue after testing it further.

Fixed.  There wasn't enough code in my description for anyone to figure this out.  The issue was that i'm learning HTML, PHP and javascript using AJAX at the same time. I'm making strange mistakes but I guess that's how you learn.

Here is the original issue.  I've left out the Javascript function and all the PHP because you don't need it.

Code:

//SELECT box 1
<select name="person" id="person" onChange="showData(this.options[this.selectedIndex].value);">
       <option>John</option>
       <option>Jane</option>
</select>

//SELECT box 2
<select name="region" id="region">
       <option>Canada</option>
       <option>US</option>
</select>

Notice my misunderstanding.  'value' is an attribute NOT the text between the tags.  I'm calling for a value that doesn't exist. For some reason, Safari, Chrome and Firefox understand my mistake and do what they think I want.  It's not Microsofts fault this time lol.

Here is the fix:

Code:

//Select box 1
<select name="person" id="person" onChange="showData(this.options[this.selectedIndex].value);">
      <option value="John">John</option>
      <option value="Jane">Jane</option>
</select>

//SELECT box 2
<select name="region" id="region">
      <option value="Canada">Canada</option>
      <option value="US">US</option>
</select>

Hehehe replying to your own post nice one.

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