ต้องการ sort ข้อมูลใน gridview ค่ะแล้วเกิด Error Page_gridview.SortCommand(object, System.Web.UI.WebControls.GridViewSortEventArgs)' is inaccessible due to its protection level

String strFields = "id_debt";
    protected void Page_Load(object sender, EventArgs e)
    {
          
    }

    void binddata()
    {
        string StrConn = WebConfigurationManager.ConnectionStrings["ConnectDB"].ToString();
        SqlCommand objCmd = new SqlCommand();
        SqlConnection Conn = new SqlConnection(StrConn);
        // String condi = "where  1=1 ";
        string sqlsm;
        sqlsm = "select * from DEBT ORDER BY " + strFields + " ASC";
        Conn.Open();
        SqlDataAdapter da = new SqlDataAdapter(sqlsm, Conn);
        DataSet ds = new DataSet();
        da.Fill(ds, "DEBT");




        gv.DataSource = ds.Tables["DEBT"];
        gv.DataBind();
    }

    void Sort(object sender, GridViewSortEventArgs e)
    {
        strFields = e.SortExpression;
        binddata();
    }



    protected void Button1_Click(object sender, EventArgs e)
    {
        binddata();
    }

protected void Page_Load(object sender, EventArgs e)
{
     gridview.Sorted += new EventHandler(gridview_Sorted); // add event to gridview
}
protected void gridview_Sorted(object sender, GridViewSortEventArgs e)
{

}