无法使用正确的信息登录，页面只是刷新

这是问题所在，我正在尝试使用正确的信息登录（通过phpmyadmin进行三重检查），但它所做的只是重定向回登录页面，就像信息不正确一样。

登录表格（页面顶部）

    <?php
      session_start();
      include "includes/class.users.php";
      if(isset($_POST['login'])) {
        $email = $_POST['email'];
        $password = $_POST['password'];
        $users->login($email, $password);
      }
    ?>

登录表格

<form method="POST" action="" name="login">
    <div id="wrappermiddle">
    <h2>Login</h2>
    <div id="username_input"> 
    <div id="username_inputleft"></div>
        <div id="username_inputmiddle">
        <input name="email" type="text" id="myusername" placeholder="Email Address">
        <img id="url_user" src="./images/mailicon.png" alt="">      
        </div><!--ends username_inputmiddle-->
        <div id="username_inputright"></div>                   
    </div><!--ends username_input-->
   <div id="password_input">
    <div id="password_inputleft"></div>
        <div id="password_inputmiddle">       
        <input name="password" type="password" id="mypassword" placeholder="Password">
        <img id="url_password" src="./images/passicon.png" alt="">        
        </div><!--ends password_inputmiddle-->
     <div id="password_inputright"></div>
    </div><!--ends password_input-->
<div id="submit"> 
<input type="image" src="./images/submit.png" name="login" value="Login">      
</form>

类.用户.php

<?php
  include "class.database.php";
  class Users extends Database {
    public function login($email, $password) {
      $stmt = $this->mysqli->prepare("SELECT email, password FROM members WHERE email = ? AND password = ? LIMIT 1");
      $stmt->bind_param('ss', $email, $password);
      $stmt->execute();
      $stmt->bind_result($email, $password);
      $stmt->store_result();
      if($stmt->num_rows == 1) {
        while($stmt->fetch()) {
          session_start();
    $_SESSION['loggedin'] = true;
          header("Location: dashboard.php");
        }
      } else {
          return false;
      }
      $stmt->close();
      $stmt->free_result();
    }
  }
  $users = new users();
?>

仪表板.php在顶部

 <?PHP
session_start();
if (isset($_SESSION['loggedin']) && $_SESSION['loggedin'] == true) {
    } else {
header ("Location: index.php");
}
?>

编辑 - 我尝试使用错误的密码登录，但出现错误 - 出现错误

当我使用正确的信息登录时，如果只是刷新登录页面。