Why My Webservice Throw Exception When I Execute My Stored Procedure ?

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C#

SQL

server

service

web

When I check the url in my browser my web service work correctly but when I call my link from my store procedure throw exception like this

System.InvalidOperationException: Request format is invalid: .
at System.Web.Services.Protocols.HttpServerProtocol.ReadParameters()
at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()

my web service is:

[WebMethod]
   public string Upload(string WarrantyCode, string Serial, string ProductTitle, string ShopCenter, string AddDate, string Bill)
   {
       SqlCommand cmd = new SqlCommand();
       cmd.Connection = new SqlConnection(Roozbeh.CnnStr);
       cmd.CommandText = "INSERT INTO Guarranty VALUES (@WarrantyCode, @Serial, @ProductTitle, @ShopCenter, @AddDate, 1, @Bill)";
       cmd.Parameters.AddWithValue("@WarrantyCode", WarrantyCode);
       cmd.Parameters.AddWithValue("@Serial", Serial);
       cmd.Parameters.AddWithValue("@ProductTitle", ProductTitle);
       cmd.Parameters.AddWithValue("@ShopCenter", ShopCenter);
       cmd.Parameters.AddWithValue("@AddDate", AddDate);
       cmd.Parameters.AddWithValue("@Bill", Bill);
       try
       {
           cmd.Connection.Open();
           cmd.ExecuteNonQuery();
           return "Roozbeh"; //OK
       }
       catch (Exception ex)
       {
           return ex.Message;
       }
       finally
       {
           cmd.Connection.Close();
       }
   }

and my store procedure is:

CREATE PROC Upload
AS
DECLARE @WarrantyCode AS NVARCHAR(20)
DECLARE	@Serial AS NVARCHAR(50) 
DECLARE	@ProductTitle AS NVARCHAR(50) 
DECLARE	@ShopCenter AS NVARCHAR(70) 
DECLARE	@AddDate AS NVARCHAR(50) 
DECLARE	@Bill AS NVARCHAR(50) 



SET     @WarrantyCode = '123456'
SET	@Serial = '123456'
SET	@ProductTitle= '123456' 
SET	@ShopCenter= '123456'
SET	@AddDate = '2014-01-01'
SET	@Bill = '123456'


Declare @Obj as Int;
Declare @Uri as Varchar(8000);
Declare @Response as Varchar(8000);
DECLARE @hr AS INT
 
 
    SET @Uri = 'http://MY IP GOES HERE:9671/MyWebService.asmx/Upload?WarrantyCode=' + @WarrantyCode + '&Serial=' + @Serial + '&ProductTitle=' + @ProductTitle + '&ShopCenter=' + @ShopCenter + '&AddDate=' + @AddDate + '&Bill=' + @Bill   
    EXEC sp_OACreate 'MSXML2.ServerXMLHttp.3.0', @obj OUT
    EXEC sp_OAMethod @obj, 'open', NULL, 'POST', @Uri, false
    EXEC sp_OAMethod @obj, 'send'
    EXEC sp_OAGetProperty @obj, 'ResponseText', @Response OUTPUT
 
       SELECT @Response AS [response], CHARINDEX('amiressami.com', @Response) AS IsOK, CHARINDEX('Hello', @Response) AS Result
    EXEC sp_OADestroy @obj

RETURN

created link by my SP is:

http://MY IP:9671/MyWebService.asmx/Upload?WarrantyCode=123456&Serial=123456&ProductTitle=123456&ShopCenter=123456&AddDate=2014-01-01&Bill=123456

it work on browser correctly but in SP not work