Problem with contact form - redirects to blank page

    <?php
require_once("../inc/config.php");
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = trim($_POST["name"]);
    $email = trim($_POST["email"]);
    $date = ($_POST["date"]);

        if ($name == "" OR $email == "") {
            $error_message = "Hmm, you seem to have forgotten your name or email!" ;
        }

        if (empty($date)) {
            $error_message = "You haven't picked a date! We need to know when you can make it!";
        }

        if (!isset($error_message) && $_POST["address"] != "") {
            $error_message = "Your form submission has an error.";
        }

        require_once(ROOT_PATH . "inc/phpmailer/class.phpmailer.php");
        $mail = new PHPMailer();

        if (!isset($error_message) && !$mail->ValidateAddress($email)){
            $error_message = "You must specify a valid email address.";
        }
        if (!isset($error_message)) {
            $email_info = "";
            $email_info = $email_info . "Name: " . $name . "<br/>";
            $email_info = $email_info . "Email: "  . $email . "<br/>";
            $email_info = $email_info . "Dates: " . $date;

            $mail->SetFrom($email, $name);
            $address = "digitalshadeuk@gmail.com";
            $mail->AddAddress($address, "Life List Party");
            $mail->Subject    = "Life List Party Info From " . $name;
            $mail->MsgHTML($email_body);
            if($mail->Send()) {
                header("Location: " . BASE_URL . "attend/?status=thanks");
                exit;
            } else {
            $error_message = "There was a problem sending the email: " . $mail->ErrorInfo;
            }
        }
}
?><?php

include (ROOT_PATH . '/inc/header.php'); ?>

<div class="grid_12">

    <?php if (isset($_GET["status"]) AND $_GET["status"] == "thanks") { ?>

        <div class="infohead thanks">
            <span>THANKS!</span><br />
            We'll be in touch shortly to confirm the date :)
        </div>

    <?php } else { ?>

    <?php
            if (!isset($error_message)) {
                    echo '<div class="infohead">WANNA COME?</div>';
            } else {
                    echo '<div class="message">' . $error_message . '</div>';
                }
                ?>

    <form method="post" action="<?php echo BASE_URL; ?>attend/">
    <table>
        <tr>
            <td>
                <input type="text" name="name" id="name" placeholder="Name" value="<?php if (isset($name)) { echo htmlspecialchars($name); } ?>">
            </td>
        </tr>
        <tr>
            <td>
                <input type="text" name="email" id="email" placeholder="Email" value="<?php if (isset($email)) { echo htmlspecialchars($email); } ?>">
            </td>
        </tr>
        <tr>
            <td>
                <input type="checkbox" name="date[]" value="1" class="checkbox"><label>4-5th January</label>
                <input type="checkbox" name="date[]" value="2" class="checkbox"><label>11-12th January</label>
                <input type="checkbox" name="date[]" value="3" class="checkbox"><label>18-19th January</label>
                <input type="checkbox" name="date[]" value="4" class="checkbox"><label>25-26th January</label>
            </td>
        </tr>
        <tr style="display: none;">
            <th>
                <label for="address">Address</label>
            </th>
            <td>
                <input type="text" name="address" id="address">
                <p>Humans: Please leave this field blank.</p>
            </td>
        </tr>
    </table>
    <input type="submit" value="I'm in!">
    </form>
    <?php } ?>
    </div>
    <?php include (ROOT_PATH . '/inc/footer.php'); ?>