Ajax :: Unable To Get Posted Variables To Work

I am using ajax in my site and want to implement a friend request button. When a user clicks this button their userid and the userid of the friend thwey are requesting will go into a table called notifications in my mysql database. This works fine in regular html/php with javascript disabled but not when using javascript/ajax.

Here's my code which may clarify things:-

Code:

<script type="text/javascript">
function makeRequest(friendrequestloggedinuserid, friendrequestuserid)
{
if (window.XMLHttpRequest)

[Code]....

The above code works perfect if javascript is disabled and the button is clicked as the new row is inserted into the database however if javascript is enabled the alert shows inidicating the ajax file is working but the new row is not inserted. Is this something to do with the POST process between my javascript code and my ajax_processrequests.php file?

BTW $loggedinuserid and $userid are retrieved earlier on in my code but showing how they are retrieved is irrelevant to this because I know they are present at the point of the above code.