JSON syntax error on Windows 2008
===

I'm trying to implement a JSON call to simulate AJAX on a certain page where an AJAX panel isn't a viable option.

I want call my .aspx page when a State is selected from a drop down and populate the Counties drop down.

in my State dropdown, I have this call:

onchange="jsonDropDownLoader('COUNTIES', this, 'Content2_DDLCounties')"

That call is on the page and the code is here:
    
    function jsonDropDownLoader(sType, oParent, oChild) {
      var lstrChild = document.getElementById(oChild);
      var lstrFilter = ""

      if (oParent.value > "") {
        lstrFilter = oParent.value
      }

      lstrChild.options.length = 0;
      if (oParent.value > "") {
        var JSONobject = {};
        var http_request = new XMLHttpRequest();
        url = "/AltairWeb.NET/RS/jsonDropDownLoader.aspx?TYPE=" + sType + "&FILTER=" + lstrFilter
        http_request.open("GET", url, false);
        http_request.onreadystatechange = function () {
            var done = 4, ok = 200;
            if (http_request.readyState == done && http_request.status == ok) {
                JSONobject = JSON.parse(http_request.responseText);
            }
        };
        http_request.send(null);
        var JSONarray = eval('(' + http_request.responseText + ')').data
        for (var i = 0; i < JSONarray.length; ++i) {
            var optn = document.createElement("OPTION");
            optn.text = JSONarray[i].text;
            optn.value = JSONarray[i].value;
            lstrChild.options.add(optn);
        }
      }
    }

It returns a string which I then use to populate the County drop down.

I'm getting data back, but it's not rendering on your QA server. Using the developer tools with IE8, I can see that I have a error on this line:

    JSONobject = JSON.parse(http_request.responseText);
it says that JSON is not declared.

It says I also have a syntax error on this line:

    var JSONarray = eval('(' + http_request.responseText + ')').data

This works perfectly on my development box. However, my development box has WinXP / IIS 5 on it, whereas, our QA server is a Win2008 server with IIS7.5.  We have new development boxes coming, but until then, I'm stuck with the XP machine.

Since it works locally, it seems like it must be a security issue with either Windows or IIS on the QA server, possibly with the http_request call, but I can't find anything via google that has helped me figure this out.

I know I've seen posts that JSON.parse is not supported by IE prior to IE9, but this works perfectly in IE8 when I point to my dev server, but not when I point to the QA server, so it doesn't seem to be a browser issue.
Any ideas?

Thanks in advance!
Tim