c# - 按钮 BuyNow 无法使用超过 50 美元的金额

Question

嗨，我做了一个动态按钮，只有当金额<30 美元，沙箱打开并且付款完成，IPN 也可以正常工作时，它才能正常工作。但是，如果我尝试以金额=50.00 或更高的金额付款，则单击按钮转到 www.paypal.com 并且无法完成付款，IPN 历史记录也不会显示该付款。有人能帮我吗。谢谢

在 C# asp.net 中编程

这是代码：

    protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
    {

        Session["PayPal_Redirected"] = "True";

        StringBuilder url = new StringBuilder();

        // strPP->SandBox
        url.Append(this.strPP + cmd);

        url.Append(HttpUtility.UrlEncode(this.business));
        url.AppendFormat("&item_name={0}", HttpUtility.UrlEncode(this.item_name));
        url.AppendFormat("&image_url={0}", HttpUtility.UrlEncode(this.logo));
        url.AppendFormat("&no_shipping={0}", HttpUtility.UrlEncode(this.no_shipping));
        url.AppendFormat("&return={0}", HttpUtility.UrlEncode(this.return_value));
        url.AppendFormat("&cancel_return={0}", HttpUtility.UrlEncode(this.cancel_return));
        url.AppendFormat("&currency_code={0}", HttpUtility.UrlEncode(this.currency_code));
        url.AppendFormat("&amount={0}", HttpUtility.UrlEncode(this.amount));
        url.AppendFormat("&item_name={0}", HttpUtility.UrlEncode(this.item_name));
        url.AppendFormat("&item_number={0}", HttpUtility.UrlEncode(this.item_number));
        url.AppendFormat("&custom={0}", HttpUtility.UrlEncode(this.os0));
        url.AppendFormat("&src={0}", HttpUtility.UrlEncode(this.src));
        url.AppendFormat("&sra={0}", HttpUtility.UrlEncode(this.sra));
        url.AppendFormat("&notify_url={0}", HttpUtility.UrlEncode(this.notify_url)); 
        Response.Redirect(url.ToString());
        return;
    }