Why the server side behavior of LoadVars() not consistent?

Question

In my server side script for FMS app,there is such code:
var lv = new LoadVars();
var params = new LoadVars();
lv.send("http://mysite.com/registerVideo.php", params, "POST");
The expected behavior is that the request will be as if sent directly from the browser,thus SESSION information is not lost ,which is the exact behavior for my computer.
But it's not the case for my boss --- session information is lost for him.
Why the server side behavior of LoadVars() not consistent?
What do I need to do to make sure session information is not lost @ server side ?

Answer 1

Oops,why this feature has always worked like charm for me only??
Below is the server side request caught from firebug:
POST registerVideo.php
http://mysite.net/registerVideo.php
200 OK
mysite.net
115ms
ParamsHeadersPostPutResponseCacheHTML
Response Headersview source
Server
nginx/0.7.67
Date
Tue, 29 Mar 2011 14:45:31 GMT
Content-Type
text/html
Transfer-Encoding
chunked
Connection
keep-alive
Vary
Accept-Encoding
X-Powered-By
PHP/5.2.14
Expires
Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control
no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma
no-cache
Content-Encoding
gzip
Request Headersview source
Host
mysite.net
User-Agent
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.13) Gecko/20100914 Firefox/3.5.13
Accept
text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language
en-us,en;q=0.5
Accept-Encoding
gzip,deflate
Accept-Charset
ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive
300
Connection
keep-alive
Cookie
pass=angel333; user=liying123; PHPSESSID=8m966mbd070tsdqqodnncesbj5
Source
Referer: http://mysite.net/flash/main.swf?sessionId=8m966mbd070tsdqqodnncesbj5 Content-type: application/x-www-form-urlencoded Content-length: 35 name=test&record=live&action=insert