Hi friends,

i am trying to download excel with the formt xlsx but its downloading only .xls format.. Attached code for reference.. please Help.

        public string GetDemandforecastingExcelTemplate(string period, string key) // New
        {        
          string  _html = ""; 
            try
            {
                _sqlParameter = null;
                _sqlCommand = "[SGGD_SEK].[USP_AG_GET_DEMAND_FORECASTING]";
                _sqlParameter = new SqlParameter[] {
                new SqlParameter("@keyWord","Template"),
                new SqlParameter("@User_Code", Session["UserCode"].ToString()),
                new SqlParameter("@XML",""),
                new SqlParameter("@Period",period), 
                new SqlParameter("@WithData",key),
                new SqlParameter("@ReportType",""),
                 new SqlParameter("@FILTERKEYWORD",""),
                new SqlParameter("@FilterValue",""),
                new SqlParameter("@isSuccess","0")
            };
                _sqlHelper = new SQLHelper();
                _businessHelper = new BusinessHelper();
                _dataTable = _sqlHelper.GetDataTable(_sqlCommand, _sqlParameter);
                string attachment = "attachment; filename=city.xlsx";
                Response.ClearContent();
                Response.AddHeader("content-disposition", attachment);
                Response.ContentType = "application/vnd.ms-excel";
                string tab = "";
                foreach (DataColumn dc in _dataTable.Columns)
                {
                    Response.Write(tab + dc.ColumnName);
                    tab = "\t";
                }
                Response.Write("\n");
                int i;
                foreach (DataRow dr in _dataTable.Rows)
                {
                    tab = "";
                    for (i = 0; i < _dataTable.Columns.Count; i++)
                    {
                        Response.Write(tab + dr[i].ToString());
                        tab = "\t";
                    }
                    Response.Write("\n");
                }
                Response.End();  
            }
            catch (Exception ex)
            {
                if (ex.Message == "Object reference not set to an instance of an object.")
                {
                    _html = "SESSION~";
                }
            }
            return _html;          
        }