Pasar total a paypal

[putorotupal]

Estoy usando esto que encontré.

Código:

private void Page_Load(object sender, System.EventArgs e)
  {
   // Put user code to initialize the page here
   string buttontest = "";

   buttontest = buttontest + "<form action=\"https://www.paypal.com/cgi-bin/webscr\" method=\"post\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"cmd\" value=\"_xclick\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"business\" value=\"[email protected]\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"item_name\" value=\"test\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"item_number\" value=\"123\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"amount\" value=\"10.00\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"currency_code\" value=\"USD\">";
   // Prepopulation
   buttontest = buttontest + "<input type=\"hidden\" name=\"first_name\" value=\"Tony\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"last_name\" value=\"Blair\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"address1\" value=\"10 Downing Street\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"city\" value=\"London\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"state\" value=\"London\">"; //Use this field for the UK County
   buttontest = buttontest + "<input type=\"hidden\" name=\"zip\" value=\"SW1 2AA\">";
   buttontest = buttontest + "<input type=\"hidden\" name=\"country\" value=\"GB\">";

   buttontest = buttontest + "<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!\">";
   buttontest = buttontest + "</form>";

   Label1.Text = buttontest;

  }

Pero lo he querido hacer para que parezca un carrito pero no me funciona.

Código:

string buttontest = "";

            buttontest = buttontest + "<form action=\"https://www.paypal.com/cgi-bin/webscr\" method=\"post\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"cmd\" value=\"_cart\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"upload\" value=\"1\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"business\" value=\"[email protected]\">";

            buttontest = buttontest + "<input type=\"hidden\" name=\"item_name_1\" value=\"Articulo 1\">";                       
            buttontest = buttontest + "<input type=\"hidden\" name=\"amount_1\" value=\"" + total + "\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"quantity_1\" value=\"1\">";           

            buttontest = buttontest + "<input type=\"hidden\" name=\"item_name_2\" value=\"Articulo 2\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"amount_2\" value=\"" + total2 + "\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"quantity_2\" value=\"1\">";
           
                       

            buttontest = buttontest + "<input type=\"hidden\" name=\"currency_code\" value=\"EUR\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"undefined_quantity\" value=\"1\">";
            buttontest = buttontest + "<input type=\"hidden\" name=\"lc\" value=\"ES\">";
            //buttontest = buttontest + "<input type=\"hidden\" name=\"bn\" value=\"PP-BuyNowBF\">";
            buttontest = buttontest + "<input type=\"image\" src=\"https://www.paypal.com/en_US/i/btn/x-click-but23.gif\" border=\"0\" name=\"submit\" alt=\"Realice pagos con PayPal: es rápido, gratis y seguro.\">";
            buttontest = buttontest + "</form>";

Que es lo que hago mal.

Gracias.

C.6