PayPal定期付款不返回成功页面中的帖子值

Question

我正在使用多余的字段（例如a3，t3，p3，src，sra，srt和cmd = _xclick-subscriptions）进行重复付款。整个过程已经完成，但是当我返回成功页面时，发布数据还没来，我不明白是什么问题。

<form id="paypal-donate-frm" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" >
            <input type="hidden" name="business" value="sudeb91@gmail.com">
            <input type="hidden" name="cmd" value="_xclick-subscriptions" >
            <input type="hidden" name="item_name" value="Chabadnorge donation">
            <input type="hidden" name="tx" value="TransactionID">
            <input type="hidden" name="item_number" value="donation">
            <input type="hidden" name="amount" id="onetimeamt">
            <input type="hidden" name="currency_code" value="USD">
            <input type="hidden" name="a3" id="finalamt" >
            <input type="hidden" name="p3" value="1">
            <input type="hidden" name="t3" value="M">
            <input type="hidden" name="post_donation_id" id="post_donation_id" value="">
            <input type="hidden" name="return" value="https://xyz.no/donatesubmit/"> 
            <input type="hidden" name="cancel_return" value="https://xyz.no/cancel/"
            <div class="paypalbackground">
            <input class="paypalsubmit" style="display:none;" type="image" 
            src="https://xyz.no/wp-content/uploads/2018/12/PayPal.png"
            alt="Donate">
            <img alt="" width="1" height="1"
            src="https://xyz.no/wp-content/uploads/2018/12/PayPal.png" >
            <input type="hidden" name="rm" value="2">
            <input type="submit" name="donate" value="Donate">
      </form>