Please help: response text from POST is empty string

[GregH]

I followed through the execution of the javascript function below using Firebug (and Firefox 1.5.0.7). I enter the callback method as expected, but the string is empty (""). Can anyone spot my error?

Thanks !!

-- Greg

function AddNewCategory()
{
var new_cat = document.NewLibraryItem.new_category.value;
var ajaxReqNewCat = GetAjaxRequest();

if(ajaxReqNewCat)
{
ajaxReqNewCat.onreadystatechange = function()
{
var text = ajaxReqNewCat.responseText;
var stall = ajaxReqNewCat.responseText;
}

ajaxReqNewCat.open("POST", "InsertCategory.php", true);
ajaxReqNewCat.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

var inStr = "new_cat=" + new_cat + "&parent_lft=" + selectedLft;

ajaxReqNewCat.send(inStr);
}
}


Just for testing, I made the InsertCategory.php file very simple.

<?php
echo "exited early";
?>