Connecting CI 3.1.3 to SQL Server 2016 Problem

I never use SQL Server before, so i still don't know why this happen. Huh

I'm running XAMPP v3.2.2 with PHP 7.1.1 with Thread Safety Enabled
SQL Server 2016 on Windows 10
i have installed ODBC driver 13
and have copy of Microsoft Driver for PHP for SQL Server 4.0 to my PHP extension and registering it to php.ini file.

the problem is, i keep getting this error when trying to connect to SQL Server 2016.

Code:

An uncaught Exception was encountered

Type: Error

Message: Call to undefined function sqlsrv_connect()

Filename: C:\xampp\htdocs\sideka\system\database\drivers\sqlsrv\sqlsrv_driver.php

Line Number: 144

Backtrace:

File: C:\xampp\htdocs\sideka\index.php

Line: 315

Function: require_once

And this is my database.php settings

Code:

$active_group = 'default';

$query_builder = TRUE;

$db['default'] = array(

    'dsn'    => '',

    'hostname' => 'tcp:127.0.0.1,1433',

    'port' => '1433',

    'username' => 'sa',

    'password' => 'a1a2a3',

    'database' => 'sideka',

    'dbdriver' => 'sqlsrv',

    'dbprefix' => '',

    'pconnect' => FALSE,

    'db_debug' => FALSE,

    'cache_on' => FALSE,

    'cachedir' => '',

    'char_set' => 'utf8',

    'dbcollat' => 'utf8_general_ci',

    'swap_pre' => '',

    'encrypt' => FALSE,

    'compress' => FALSE,

    'stricton' => FALSE,

    'failover' => array(),

    'save_queries' => TRUE

);

Did anyone know to solve the problem? Any help is appreciated. Rolleyes