XMLHttpRequest request to php page gives server 404 ( page not found)

[umen]

hello all
im doing simple XMLHttpRequest request to the server tested both in apache 2.2 and
lighttpd and they both gives me the same results
i have client side code that lookes liks this
index.php

var rqo;
function req(d)
{
   if (d != "")
   {
        document.getElementById("details_data").innerHTML = "Fetching Data ...." ;
        rqo = createRequestObject();
        var qry = encodeURIComponent(d);
        rqo.open('GET',qry,true); //<< also tried false here ... 
        rqo.onreadystatechange = handleDetailsHttpResponse ;      
        rqo.send(null);

        return false;
    }
}

function handleDetailsHttpResponse() {
  var results = "";
  if (rqo.readyState == 4) {
    results = rqo.responseText;
    document.getElementById("details_data").innerHTML = results;
  }
}

in the d variable the value is :
index.php?Action=1&data_input=059652983X&data_category=All
now in the lighttpd for example im getting the error that file is not found 404

2009-02-07 22:40:15: (response.c.453) -- logical -> physical 
2009-02-07 22:40:15: (response.c.454) Doc-Root     : /var/www/ 
2009-02-07 22:40:15: (response.c.455) Rel-Path     : /index.php?Action=1&data_input=059652983X&data_category=All 
2009-02-07 22:40:15: (response.c.456) Path         : /var/www/index.php?Action=1&data_input=059652983X&data_category=All 
2009-02-07 22:40:15: (response.c.473) -- handling physical path 
2009-02-07 22:40:15: (response.c.474) Path         : /var/www/index.php?Action=1&data_input=059652983X&data_category=All 
2009-02-07 22:40:15: (response.c.530) -- file not found 
2009-02-07 22:40:15: (response.c.531) Path         : /var/www/index.php?Action=1&data_input=059652983X&data_category=All 
2009-02-07 22:40:15: (response.c.116) Response-Header: 
HTTP/1.1 404 Not Found
Content-Type: text/html
Content-Length: 345
Date: Sat, 07 Feb 2009 20:40:15 GMT
Server: lighttpd/1.4.19

but the file is there for sure !!! this is the file im doing the request form ..
can someone please explain me what im doing wrong ?
Thanks