Procedure or function 'INSERTMARKS' expects parameter '@i', which was not supplied.

USE [School]
GO
/****** Object:  StoredProcedure [dbo].[INSERTMARKS]    Script Date: 12/21/2012 13:57:58 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		VARUN
-- Create date: 21/12/2012
-- Description:	
-- =============================================
ALTER PROCEDURE [dbo].[INSERTMARKS] 
	-- Add the parameters for the stored procedure here
	@name varchar(50),
	@sub varchar (50),
	@m tinyint,
	@i smallint output,
	@s smallint output
	
AS
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	SET NOCOUNT ON;

    -- Insert statements for procedure here
	SELECT @i=Roll_no from student where Name=@name;
	select @s=Subject_ID from subject where subject_name=@sub;
	insert into marks values(@i,@s,@m);
END

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;


public partial class marks : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        Response.Redirect("Default.aspx");
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string conn = "Data Source=.;Initial Catalog=School;Integrated Security=True";
        SqlConnection con = new SqlConnection(conn);
        con.Open();
        SqlCommand cmd = new SqlCommand("INSERTMARKS",con);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "INSERTMARKS";
        cmd.Parameters.Add("@name",SqlDbType.VarChar).Value=DropDownList1.SelectedValue.Text;
       cmd.Parameters.Add("@sub",SqlDbType.VarChar).Value=DropDownList2.SelectedValue;
        cmd.Parameters.Add("@m",SqlDbType.TinyInt).Value=TextBox3.Text;
       // cmd.Parameters.Add("@i", SqlDbType.SmallInt);
        //cmd.Parameters.Add("@s", SqlDbType.SmallInt);
        cmd.ExecuteNonQuery();
        con.Close();

        Response.Redirect("Default.aspx");
        
    }
}