Invalid rank specifier: expected ',' or ']'

Library lib = new Library();
        foreach (GridViewRow row in grdAdminInitiate.Rows)
        {
            sEmpCode = row.Cells[0].Text.Trim();
            sGrade = row.Cells[3].Text.Trim();
            sStatus = row.Cells[8].Text.Trim();
            sToEmail = row.Cells[4].Text.Trim();

            String[] ArrGrade = new String[7] { "M-12", "M-11", "M-10", "M-9", "M-8", "M-7", "M-6", "M-5", "M-4", "M-3", "M-2", "M-1" };
            int iIsMailSentForSelf = 0;