php – 解决会话变量问题

if (isset($_SESSION['invite_error'])) {
   echo $_SESSION['invite_error'];
   unset($_SESSION['invite_error']);
}

但是,如果我离开此页面并返回到该页面,则仍会显示错误消息.如果我离开并再次回来,它将会完成.当我刷新那个页面时它是一样的… 1刷新不会摆脱它,但2会.我不能破坏整个会话,我只是想取消设置这个变量. PHP版本是5.2.5 build 6,注册全局变量是关闭的,我在这个页面的顶部调用了session_start(),我也尝试过使用no-cache标头.

编辑：添加完整代码.

<?php 
ob_start();
session_start();

$user_id = $_SESSION['user_id'];
$user_name = $_SESSION['user_name'];

if ($user_id==null) header("Location: /login.php");

if (isset($_SESSION['invite_errors'])) {

    $error = $_SESSION['invite_errors'];
    unset($_SESSION['invite_errors']);

}

require_once("ui/header.php");
?>



<div id="invite" class="content">

    <?php if($error) { ?>
        <div class="errors round">
            <?php echo $error ?>
        </div>
    <?php } ?>

    <h3>Invite Your Friends</h3>

    <div class="invite-form">
        <form method="post" action="controllers/invite.php">
            <div class="row">
                <textarea class="txt-area" name="emails" id="emails" rows="5"></textarea>
                <div class="tip">Separate multiple email addresses with,</div>
            </div>
            <div class="row-submit">
                <input type="submit" name="submit" id="submit" class="submit-btn" value="Submit" />
            </div>
        </form>
    </div>

</div>

<?php
    require_once("ui/footer.php");
?>