将html form 内容写到后台

  <form action="https://www.paypal.com/cgi-bin/webscr" method="post">

  <input type="hidden" name="cmd" value="_xclick" >

  <input type="hidden" name="business" value="test@test.com" >

  <input type="hidden" name="item_name" value="testtest" >

  <input type="hidden" name="currency_code" value="USD" >

  <input type="hidden" name="amount" value="100.00" >

    <input type="image" src="https://www.paypal.com/en_US/i/btn/x-click-but23.gif" border="0"

        name="submit" alt="Make payments with PayPal - it's fast, free and secure!">

    </form>

 protected void Button1_Click(object sender, EventArgs e)

    {

        string postData = "";

        postData += "cmd=_xclick";

        postData += "&business=test@test.com";

        postData += "&item_name=testtest";

        postData += "&currency_code=USD";

        postData += "&amount=100.00";

        byte[] data = Encoding.Default.GetBytes(postData);

        HttpWebRequest ppRequest = (HttpWebRequest)

         WebRequest.Create("https://www.paypal.com/cgi-bin/webscr"); ;

        ppRequest.Method = "POST";

        ppRequest.ContentType = "application/x-www-form-urlencoded";

        ppRequest.ContentLength = data.Length;



        Stream ppStream = ppRequest.GetRequestStream();

        ppStream.Write(data, 0, data.Length);

        ppStream.Close();



        HttpWebResponse ppResponse = (HttpWebResponse)ppRequest.GetResponse();

        StreamReader sr = new StreamReader(ppResponse.GetResponseStream());

        string strResult = sr.ReadToEnd();

        sr.Close();

 

        Response.Clear();

        Response.Write(strResult);

        Response.End();



    }

这样提交过去不对。
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我用你的代码  请求时请求过去了  
但是显示了
Sorry — your last action could not be completed

不知道是不是LZ的参数有误还是怎么的
------解决方案--------------------