How to correctly include php files in smarty so that the contents of tpl files are displayed?

Question

PHP

The problem is that when including php files in index.php, the content pages become empty, without any html/php code. Actually, here is my index.php, maybe I'm doing something wrong, I will be very grateful for your help.

<?php

error_reporting(0);
define('INCLUDE_CHECK',true);
include 'config.php'; 
include 'auth.php';
require '/libs/Smarty.class.php';

$path = dirname(__FILE__);
define('GLI',true);
$q = mysql_query("SELECT `name` FROM `rust_templates` WHERE `name`='default';",$sql);
$theme = mysql_result($q,0);
$tpl = new Smarty();
$theme_path = './templates/'.$theme.'/';
$tpl->template_dir = $theme_path;
$tpl->assign('path', $theme_path);
$tpl->caching = false;
//$tpl->compile_dir = './cache/';
$tpl->cache_dir = './cache/';

if(empty($_SESSION['id'])) {
    // Тут делаем авторизацию
    $tpl->assign('title', 'Авторизация');
    if(isset($_GET['error'])) {
        $tpl->assign('errno', 'Неверный логин или пароль!');
        $logger->WriteLine($log_date . "Неудачная попытка авторизации с ip: " . $_SERVER['REMOTE_ADDR']);
    }
    $tpl->assign('title', 'Новости');
    include("./modules/news.php");
    $tpl->display('guest.tpl');
} else {
    if(!isset($_GET['page']) || $_GET['page'] == '') {
        $tpl->assign('title', 'Новости');
        include("./modules/news.php");
        $tpl->assign('content', 'short-story.tpl');
        $tpl->assign('welcome1', 'Добро пожаловать '.$username.'!');
    } else {
        $full_path = './theme/'.$theme.'/'.$_GET['page'].'.tpl';
        if(!file_exists($full_path)) {
            $tpl->assign('title', 'Ошибка 404');
            $tpl->assign('content', 'error.tpl');
            $tpl->assign('welcome1', 'Ошибка 404');
            $tpl->assign('welcome2', '');
        }
        if($_GET['page'] == 'buy') {
            $tpl->assign('title', 'Покупка статуса');
            include("news.php");
            $tpl->assign('welcome1', 'Покупка статуса');
            $tpl->assign('welcome2', 'Здесь вы можете купить игровой статус');
        }
        if($_GET['page'] == 'quit') {
        session_destroy();
      header("Location: index.php");
    }
    }
    $tpl->display('index.tpl');
}
mysql_close($sql);

Answer 1

What about error logs? Are there any errors in the inserted files, do the variables overlap? You can try output buffering (ob_start\ob_get_clean)