Paypal订阅未完成且未重定向到我的网站

Question

点击订阅按钮后，它会重定向到paypal，登录后付款未完成。以下是我的代码

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
<!-- Identify your business so that you can collect the payments. -->
    <input name="business" value="marchent_account@paypal.com" type="hidden">
    <!-- Specify a Subscribe button. -->
    <input name="cmd" value="_xclick-subscriptions" type="hidden">
    <!-- Identify the subscription. -->
    <input name="item_name" value="Gold Subscription Plan " type="hidden">
    <input name="item_number" value="1" type="hidden">
    <!-- Set the terms of the regular subscription. -->
    <input name="currency_code" value="USD" type="hidden">
    <input name="a3" value="50.00" type="hidden">
    <input name="p3" value="1" type="hidden">
    <input name="t3" value="M" type="hidden">
    <!-- Set recurring payments until canceled. 
    <input type="hidden" name="src" value="1"> -->
    <input name="cancel_return" value="https://www.mywebsite.com/status.php?action=cancel" type="hidden">
    <input name="notify_url" value="https://www.mywebsite.com/status.php?action=success" type="hidden">
    <!-- Display the payment button. -->
    <input name="submit" src="https://www.paypalobjects.com/webstatic/en_US/i/btn/png/btn_subscribe_113x26.png" alt="Subscribe" type="image">
    <img alt="" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" height="1" width="1">
</form>

第1步：

第2步：

登录后的金额未扣除且未重定向到我的网站。