php pdo注册不工作?

我知道这是一个非常“典型”的问题,它应该很容易做到,但我不能包庇我的头为什么它不工作?,一旦输入被添加到表单并点击“enter”,它就会简单地重定向到register.php,并从我的connect脚本返回“connected successfully”。我的数据库里什么都没有,任何我出错的地方都会很好!

HTML格式

    <form method "POST" id="regform" action="register.php">
    <input type="text" username="username" placeholder="Please enter your 
    email"/>
    <input type="text" password="password" placeholder="Please create a 
    password"/>
    <input type="submit" value="enter"/>
    </form>

连接.php

<?php

$servername = "localhost";
$dbusername = "root";
$dbpassword = "root";
$dbname = "fyp";


try{
$pdostmt = new PDO("mysql:host=$servername;dbname=$dbname",$dbusername, 
$dbpassword);
 $pdostmt->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 echo "connected succesfully";
}
catch(PDOException $e)
{
print "Error! Unable to connect: " . $e->getMessage() . "<br/>";
die();
}
?>

单文件

<?php
// Starting the session and connecting to the DB
session_start();
require_once'connect.php';

if(isset($_POST['register'])){


$username = !empty($_POST['username']) ? trim($_POST['username']) : null;
$pass = !empty($_POST['password']) ? trim($_POST['password']) : null;

$sql = "SELECT COUNT(username) AS num FROM users WHERE username = :username";
$stmt = $pdo->prepare($sql);
$stmt->bindValue(':username', $username);


$stmt->execute();


$row = $stmt->fetch(PDO::FETCH_ASSOC);


if($row['num'] > 0){
    die('That username already exists!');
}

$sql = "INSERT INTO users (username, password) VALUES (:username, 
:password)";
$stmt = $pdo->prepare($sql);

$stmt->bindValue(':username', $username);
$stmt->bindValue(':password', $passwordHash);

$result = $stmt->execute();

if($result){
    echo 'Thank you for registering with our website.';
            header("Location: index.php");
 }
    else {
        echo '<b> There has been an error please contact support </b>';
    }

}

?>

我已经为此绞尽脑汁了一段时间,任何帮助都是值得的,如果我是愚蠢的斥责我。