warunek if nie działa

<form action="register.php" method="post">
            Login: <input type="text" name="rlogin"><br>
            Password: <input type="password" name="rpassword1"><br>
            Repeat password: <input type="password" name="rpassword2"><br>
            E-mail: <input type="text" name="rmail"><br>
            <input type="checkbox" name="check"> I accept the terms and conditions <br><br><br>
            <div class="g-recaptcha" data-sitekey="recaptcha site key"></div><br>
            <input type="submit" />
        </form>

session_start();

    if (!isset($_POST['rlogin']) || !isset($_POST['rpassword1']) || !isset($_POST['rpassword2']) || !isset($_POST['rmail']))
    {
        $_SESSION['dane'] = "wypełnij dane";
        header("location: reg.php");
    } else {

        require_once "base.php";

        unset($_SESSION['null']);
}

session_start();
var_dump($_POST);// sprawdź zawartość tej tablicy
    if (!isset($_POST['rlogin']) || !isset($_POST['rpassword1']) || !isset($_POST['rpassword2']) || !isset($_POST['rmail']))
    {
        $_SESSION['dane'] = "wypełnij dane";
        header("location: reg.php");
    } else {

        require_once "base.php";

        unset($_SESSION['null']);
}