我正在尝试使用以下代码上传购物车，但是当用户点击“立即购买”按钮时，我没有显示用户可以登录付款的 PayPal 订单摘要页面，而是收到一条错误消息Your shopping cart is empty.
这是我的代码，有什么问题吗？
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<a href='cart.php?type=current' class='buttonlink previous'>Edit Order</a> <a href='checkout4_confirm.php' class='buttonlink next'>Submit Order</a>
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="hosted_button_id" value="JRECLRTYAJDKY">
<input type="hidden" name="upload" value="1">
<input type="hidden" name="business" value="XXX@XXX.XXX">
<input type="hidden" name="item_name_1" value="<?php echo $order_number; ?>">
<input type="hidden" name="item_number_1" value="1">
<input type="hidden" name="quantity_1" value="1">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_paynow_SM.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>