update

May be I found something interesting.
it may be a joomla 2.51 incompatibility

after some "rude/primitive" debugging
I saw that AUP synch.php includes "admin/includes/framework.php"
this file contains the following code

/*
* Installation check, and check on removal of the install directory.
*/
if (!file_exists(JPATH_CONFIGURATION.'/configuration.php') || (filesize(JPATH_CONFIGURATION.'/configuration.php') < 10) || file_exists(JPATH_INSTALLATION.'/index.php')) {
header('Location: ../installation/index.php');
exit();
}

I guess it quits because of the presence of the index.php
that joomla 2.51 doesn't likes.

________________________
Update 2

yes it is:I rewrote the line without the index.php check
and now it works

Idon't know if it is a bad jms installation or something wrong on my site
or actually a Joomla incompat

Please I need at least a quick temporary reply
(read the previous post)

I found that 2 joomla 2.51 files
root/admin/includes/framework.php
and root/includes/framework.php
have inside a check on the presence of the "installation" directory

If I delete the index.php checking
the problem is solved
but I am not sure
if I found really the source of the problem
or it is something wrong with the site

I have debugged the Alpha User point and found the bug in the alpha user point.

The bug is located in the
administrator\components\com_alphauserpoints\assets\synch\synch.php

They does not perform a correct joomla 1.7/2.5 initialization.

You must replace the code at the begining of the file

--- Bad code ---
define( '_JEXEC', 1 );
if (stristr( $_SERVER['SERVER_SOFTWARE'], 'win32' )) {
define( 'JPATH_BASE', realpath(dirname(__FILE__).'\..\..\..\..' ));
} else define( 'JPATH_BASE', realpath(dirname(__FILE__).'/../../../..' ));

define( 'DS', DIRECTORY_SEPARATOR );

require_once ( JPATH_BASE.DS.'includes'.DS.'defines.php' );





Please report the bug to Alpha User Point with the fix that must be put in the file.

--- Replaced by good initialisation (standard joomla 1.7/2.5 initialization) ----
define( '_JEXEC', 1 );

define('DS', DIRECTORY_SEPARATOR);

if (file_exists( dirname( dirname( dirname( dirname( dirname(__FILE__))))) .DS. 'defines.php')) {
include_once dirname( dirname( dirname( dirname( dirname(__FILE__))))) .DS. 'defines.php';
}

if (!defined('_JDEFINES')) {
define('JPATH_BASE', dirname( dirname( dirname( dirname( dirname(__FILE__))))));
require_once JPATH_BASE.'/includes/defines.php';
}

Thank you
That's soon done:

www.alphaplug.com/index.php/forum/41-gen...syncusers-fails.html