Problem with IIS and PDO oci

I'm uploading a web application, which has a php code, and specifically, PDO code to connect to an oracle database with oci.

The problem is that the php that is installed in the IIS, shows several PDO minus the one I need, and in php.ini, it is.

I need it to make my code work:

function connection(){
    try{
        $tns = '
            (DESCRIPTION =
                (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
                (CONNECT_DATA =
                    (SERVICE_NAME = XE)
                )
            )
        ';
        $pdo_string = 'oci:dbname='.$tns;
        $userBBDD = 'siade';
        $passBBDD = 'siade';
        $conn  = new PDO($pdo_string, $userBBDD, $passBBDD);
        return $conn;
    }catch(Exception $e){

        die('Error: ' . $e->GetMessage());

    }
}