SQL Server Error

I'm using the standaard sqldrv with mussel 2014 and 2016 with no problem.

Code:

$db['default'] = array(
    'dsn'    => '',
    'hostname' => 'name server\SQLEXPRESS',  //if you using sqlexpress like me
    'port' => '1433',
    'username' => 'your username',
    'password' => 'your password',
    'database' => 'Your database',
    'dbdriver' => 'sqlsrv',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => (ENVIRONMENT !== 'production'),
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE
);