在登录后页面中看不到我的会话值

Question

我有一个登录页面，当用户名和密码正确时，我会在会话中保存记录人员的ID和用户名：

$result = $conn->prepare("SELECT * FROM login WHERE username= :u AND password= :p");
$result->bindParam(':u', $user);
$result->bindParam(':p', $password);
$result->execute();
$rows = $result->fetch(PDO::FETCH_NUM);
if($rows > 0) {
    $_SESSION['username'] = $user;
    $_SESSION['login_id'] = $id_logged;
    header("location: ./pages/home.php");
}

在home.php中，我试图回应这两个会话：

<?php 
require_once('../include/global.php');
$user = $_SESSION['username'];
$id_logged = $_SESSION['login_id'];
echo $dentist_user;
echo $id_logged;
?>

但我只看到没有ID的用户名。

global.php代码是：

<?php

session_start();

    $DB_host = "localhost";
    $DB_user = "";
    $DB_pass = "";
    $DB_name = "";
    if(!isset($_SESSION['username']) && !isset($_SESSION['login_id'])){
        header("Location: ../index.php");
    }
    else{
        try
        {
             $conn = new PDO("mysql:host={$DB_host};dbname={$DB_name}",$DB_user,$DB_pass);
             $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
             $conn->exec("SET CHARACTER SET utf8mb4");
        }
        catch(PDOException $e)
        {
             echo $e->getMessage();
        }
    }
?>