DirectAdmin API - issue with show user config

[feerdispzoo]

<?php

include '../protocol/httpsocket.php';

$sock = new HTTPSocket;

$sock->connect('localhost',2222);
$sock->set_login('admin','admin_password');

$show_user='user5';

$sock->query('/CMD_API_SHOW_USER_CONFIG?user='.$show_user);
$result = $sock->fetch_parsed_body();

print_r($result);

?>

This above code return: white page with only "Array ( )"

Connection with DA is correct, because I can create user API etc.