Why Getting This Error When I Update?Additional Information: Procedure Or Function Sp_Neetha Has Too Many Arguments Specified.

Update
Additional information: Procedure or function sp_neetha has too many arguments specified.

Delete

Additional information: The connection was not closed. The connection's current state is open.

create procedure sp_neetha (@id int ,@school nchar(10),@office nchar(10),@flag nchar(10))
as
begin
if(@flag='insert')
begin
insert into neetha (id,school ,office) values(@id,@school,@office)
end
if(@flag='delete')
begin
delete from neetha where id=@id
end
if(@flag='select')
begin
select * from neetha
end
if(@flag='update')
begin
update neetha set school=@school,office=@office where id=@id
end
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;
using System.Data.SqlClient;

namespace joins
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {


            if(!IsPostBack)
            {


                grid();
            }
        }

        SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=D:\MyPractice\joins\joins\App_Data\Database1.mdf;Integrated Security=True");
        SqlCommand cmd = new SqlCommand();


        public void grid()//HERE AM GETTING ERRORS..should we pass all the values in in select query? I gave cmd.Parameters.AddWithValue("@flag", "select"); only but showing expected parameter like... y?
        {
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "sp_neetha";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@id",DbType.Int32);
            cmd.Parameters.AddWithValue("@school", DbType.String);
            cmd.Parameters.AddWithValue("@office", DbType.String);
            cmd.Parameters.AddWithValue("@flag", "select");
            
            cmd.ExecuteNonQuery();
            
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt=new DataTable();
            da.Fill(dt);
            con.Close();
            GridView1.DataSource = dt;
            GridView1.DataBind();

          

        }



        protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
        {
            GridView1.EditIndex = e.NewEditIndex;
          
            grid();
        }

        protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {

            int id =   Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Values["id"].ToString());


            TextBox txtid = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txteditid");
            TextBox txtschool = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txteditscool");
            TextBox txtoffs = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txteditoffs");
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "sp_neetha";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@id", txtid.Text);
            cmd.Parameters.AddWithValue("@school", txtschool.Text);
            cmd.Parameters.AddWithValue("@office", txtoffs.Text);

            cmd.Parameters.AddWithValue("@flag","update");

            cmd.ExecuteNonQuery();
            con.Close();
            GridView1.EditIndex = -1;
            grid();


        }


        protected void Button6_Click(object sender, EventArgs e)
        {
            grid();
        }

        protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
        {

            int id1=   Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Values["id"].ToString());
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "sp_neetha";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@id", DbType.Int32);
            cmd.Parameters.AddWithValue("@school", DbType.String);
            cmd.Parameters.AddWithValue("@office", DbType.String);
            cmd.Parameters.AddWithValue("@flag", "delete");
            grid();
           int result = cmd.ExecuteNonQuery();
           if (result==1)
           {

               grid();

            }


            con.Close();
      }

        protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {


            if(e.CommandName.Equals("add"))
            {


                TextBox txtid1 = (TextBox)GridView1.FooterRow.FindControl("txteditfooter");
                TextBox txtschool1 = (TextBox)GridView1.FooterRow.FindControl("txteditscool");
                TextBox txtoffs1 = (TextBox)GridView1.FooterRow.FindControl("txteditfooterofs");
              
                con.Open();
                cmd.Connection = con;
                cmd.CommandText = "sp_neetha";
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.AddWithValue("@id", txtid1.Text);
                cmd.Parameters.AddWithValue("@school", txtschool1.Text);
                cmd.Parameters.AddWithValue("@office", txtoffs1.Text);
                cmd.Parameters.AddWithValue("@flag", "insert");
                int result = cmd.ExecuteNonQuery();
                if(result==1)
                {

                    GridView1.EditIndex = -1;
                        grid();

                      

                }

                con.Close();




            }
        }

        protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
        {
            GridView1.EditIndex = -1;
            grid();
        }



    }
}