First, user local.protected.php. ;)
For me everything works fine with :
$conf['auth']['ad']['account_suffix'] = '@blabla.com';
$conf['auth']['ad']['base_dn'] = 'DC=blabla,DC=com';
$conf['auth']['ad']['domain_controllers'] = 'srv01.blabla.com,srv02.blabla.com'; //multiple can be given
$conf['auth']['ad']['sso'] = 0;
$conf['auth']['ad']['real_primarygroup'] = 0;
$conf['auth']['ad']['use_ssl'] = 0;
$conf['auth']['ad']['debug'] = 0;
$conf['auth']['ad']['recursive_groups'] = 1;