private void cmdGetFiles_Click(object sender, EventArgs e)
        {
            string filesDir = Path.Combine(folder, _config.BareName);
            DirectoryInfo d = new DirectoryInfo(filesDir);
            if (!d.Exists)
            {
                d.Create();
            }

             var dt = _config.GetDataTable(
                    "select  * from tb_submissions");

            var iCnt = 0;

            foreach (DataRow item in dt.Rows)
            {
                var minSub = new TurnitInSubmission(
                    item["SUB_UserId"].ToString(),
                    item["SUB_PaperId"].ToString(),
                    item["SUB_Title"].ToString()
                    );

                if (minSub.DownloadDocument(filesDir, elpSessionId.Text))
                    iCnt++;
            }
            MessageBox.Show(iCnt + " documents downloaded");
        }