Problemi Pluling: PHP Single Sign On

Salve come da titolo ho problemi con questo pluling.

Prima di tutto nel pannello aministrazione al top pagina esce questo:

Notice: Use of undefined constant __DIR__ - assumed '__DIR__' in /membri/nome_mio_membro/wp-content/plugins/phpbb-single-sign-on/common-functions.php on line 14

WordPress database error: [Table 'my_sandboxitalia.0config' doesn't exist]
SELECT config_value FROM 0config WHERE config_name = 'auth_method'

Notice: has_cap è stato chiamato con un argomento deprecato dalla versione 2.0! L'utilizzo dei livelli utenti da temi e plugin è deprecato. Utilizza ruoli e capacità.. in /membri/nome_mio_membro/wp-includes/functions.php on line 2923

Poi quando configuro il pluling, dice:

The phpBB Plugin is not activated now.

If the check didn't work correctly, you can see on the following instructions on how to manually correct the problems.

Notice : if the first test isn't correct, the following won't work, so please do it in the right order.

Wordpress Path

This is the first thing you have to set, it is the relative path to your PHPBB installation.
If the wordpress is at the root of your web folder (/www/) and your forum in the wordpress folder (www/forum/).
You will have to set forum/ as path. (don't forget the end slash)

auth_wpbb.php

This file must be copied from to /auth_wpbb.php

common.php

It seems that this file is the original common.php file.
you will have to rename this file from common.php to common-orig.php
the file is in the folder

This file must be copied from to /common.php

common-orig.php

You already did this on the previous step, this file doesn't exist by default, it's the original common.php file, because this script needs another one in place to load some libraries

auth_method

This form element only appears when the path_var is correctly set.
You have to set it to wpbb

Wordpress path:
ho scritto www.miosito.altervista.org/forum/

auth_wpbb.php
non ho capito dove si trova questo file e dove copiarlo

common.php
per questo file NON mi da errore, mi dice OK, ma nonostante tutto l'ho copiato e rinominato.

common-orig.php
e quindi? per risolvere questo errore come devo fare?

auth_method
a me dice che è ok, ma magari è ok il file e non la configurazione...