Great !
I try many many, too many things ! For a loooooooooooooong time :-(
I can't used include and opendir because my WordPress and my whmcs are on the same shared server in 2 seperate cpanel account.
So i try your method, supress the call to php file with the start_session and add it on the top ogf the WordPress header code like that:
<?php
session_start();
$db_host = "localhost";
............
Now i can access to the database, but he say that i'm not loggin.
I'm not developpeur but i understand that you check that with session, and i believe the start_session must be on the whmcs side in the php file....
If i'm right, a solution for me were to use cookie for checking login/logout ?
I understand that it is possible to use cookie method on a domain (WordPress) and his subdomain (my whmcs)
If anybody can help me before i'm going crazy, or do the job for a little fee...
Sorry for my bad English !