密码保护访问某些文件被拒绝

我正在尝试设置密码保护以使用某些文件。我遵循了一个在线教程，并获得了一些成功，但在其他情况下，尽管似乎是完全相同的操作正在执行，但仍不断调用拒绝访问的页面。

从我的登录页面，登录脚本调用一个php登录页面，它应该存储会话ID。然后，我有一个单独的页面来检查会话ID是否已存储，并且该页面(称为auth.php)包含在我试图保护的页面中。我把php代码放在文件的开头，正如我所说的，对于一些测试页面，它是有效的，但对于我需要它的页面，它会返回到拒绝访问的页面，这对我来说意味着它不能识别会话ID已经存储。我没有得到任何与连接问题有关的错误消息，所以我的重点是会话ID问题。如有任何意见，不胜感激。

包括代码:

<?php
require_once('auth.php');
?>

auth.php代码:

<?php
//Check whether the session variable SESS_MEMBER_ID is present or not
if(!isset($_SESSION['SESS_MEMBER_ID']) || (trim($_SESSION['SESS_MEMBER_ID']) == '')) {
    header("location: access-denied.php");
    exit();
}
  ?>

登录脚本代码相关部分:

//Create query
$qry="SELECT * FROM members WHERE login='$login' AND password='".md5($_POST['password'])."'";
$result=mysql_query($qry);
//Check whether the query was successful or not
if($result) {
    if(mysql_num_rows($result) == 1) {
        //Login Successful
        session_regenerate_id();
        $member = mysql_fetch_assoc($result);
        $_SESSION['SESS_MEMBER_ID'] = $member['member_id'];
        $_SESSION['SESS_FIRST_NAME'] = $member['firstname'];
        $_SESSION['SESS_LAST_NAME'] = $member['lastname'];
        session_write_close();
        header("location: member-index.php");
        exit();
    }else {
        //Login failed
        header("location: login-failed.php");
        exit();
    }
}else {
    die("Query failed");
}

完整登录码:

<?php
//Start session
session_start();
//Include database connection details
require_once('config.php');
//Array to store validation errors
$errmsg_arr = array();
//Validation error flag
$errflag = false;

//Function to sanitize values received from the form. Prevents SQL injection
function clean($str) {
    $str = @trim($str);
    if(get_magic_quotes_gpc()) {
        $str = stripslashes($str);
    }
    return mysql_real_escape_string($str);
}
//Sanitize the POST values
$login = clean($_POST['login']);
$password = clean($_POST['password']);
//Input Validations
if($login == '') {
    $errmsg_arr[] = 'Login ID missing';
    $errflag = true;
}
if($password == '') {
    $errmsg_arr[] = 'Password missing';
    $errflag = true;
}
//If there are input validations, redirect back to the login form
if($errflag) {
    $_SESSION['ERRMSG_ARR'] = $errmsg_arr;
    session_write_close();
    header("location: login-form.php");
    exit();
}
//Create query
$qry="SELECT * FROM members WHERE login='$login' AND password='".md5($_POST['password'])."'";
$result=mysql_query($qry);
//Check whether the query was successful or not
if($result) {
    if(mysql_num_rows($result) == 1) {
        //Login Successful
        session_regenerate_id();
        $member = mysql_fetch_assoc($result);
        $_SESSION['SESS_MEMBER_ID'] = $member['member_id'];
        $_SESSION['SESS_FIRST_NAME'] = $member['firstname'];
        $_SESSION['SESS_LAST_NAME'] = $member['lastname'];
        session_write_close();
        header("location: member-index.php");
        exit();
    }else {
        //Login failed
        header("location: login-failed.php");
        exit();
    }
}else {
    die("Query failed");
}

?>