Folder Permissions

I am having trouble implementing code for setting "Access All" on the folder permissions for my web folder.
I've tried a number of lines of code but I can't seem to get it right. I am running a script install.php from a test folder

like so:
www.test.com/test/install.php

I want to make /test/ 0777 permission, and it currently is set at 0755

I've tried


$FullPath = $_SERVER['DOCUMENT_ROOT']. '/Test';
echo $FullPath;
mkdir($FullPath,0777,true);
chmod($FullPath, 0777) or die ("Permission not granted for root");


also

$FullPath = '../Test';


and just plain setting the chmod as 0777 (no mkdir)... its got me stumpped and banging my head!

I have set perrimisions on this webserver before, so I can't understand why it refuses to work. In those cases I created folders first and then set the chmod, as I have a server that doesn't allow direct setting of mkdir permission, for whatever reason (which reminds me the webserver is linix based). The only thing I can think of is that some how you can't set permission of folder you are in?

Going crazy ... and thanks in advance
James

Here's some code from one of my pages.

if ((!file_exists($_SESSION["path"]))&&($_FILES['userfile']['name'] != "" ))
{
mkdir($_SESSION["path"]);
chmod($_SESSION["path"],0777);
if(!is_writable($_SESSION["my_path"]))
die('You cannot upload to the specified directory, please CHMOD it to 777.');
}
You can't apply chmod to the whole path, only to the directory, without the end slash. 'my_path' in the above code is the whole path.