Object Reference to an instance of an object

public void Gridbind()
{
    StringBuilder var1 = new StringBuilder();
    var1.Append("SELECT tblpullsms.ID,Row_number() \n");
    var1.Append("         OVER ( \n");
    var1.Append("           ORDER BY tblpullsms.createddate DESC)           AS SrNo, \n");
    var1.Append("       fm.factoryname                                      AS FactoryName, \n");
    var1.Append("       ec.enumerationvalue                                 AS FactoryType, \n");
    var1.Append("       CONVERT(VARCHAR(10), tblpullsms.createddate, 103)   AS CreatedDate, \n");
    var1.Append("       tblpullsms.mobileno, \n");
    var1.Append("       CONVERT(VARCHAR(10), tblpullsms.createddate, 103) \n");
    var1.Append("       + '  ' \n");
    var1.Append("       + CONVERT(VARCHAR(10), tblpullsms.createddate, 108) AS CreatedDate1, \n");
    var1.Append("       cd.districtname, \n");
    var1.Append("       tblpullsms.code, \n");
    var1.Append("       Sum(tblpullsms.crush)                               AS Crush, \n");
    var1.Append("       Sum(tblpullsms.prod)                                AS Prod, \n");
    var1.Append("       Sum(tblpullsms.rate)                                AS Rate, \n");
    var1.Append("       Cast(Avg(tblpullsms.recov) AS NUMERIC(18, 2))       AS Recov, \n");
    var1.Append("       ev.enumerationvalue                                 AS Division \n");
    var1.Append("FROM   dbo.tblpullsms \n");
    var1.Append("       INNER JOIN factory_master fm \n");
    var1.Append("               ON fm.factorycode = tblpullsms.code \n");
    var1.Append("       INNER JOIN enumerationvalue ec \n");
    var1.Append("               ON ec.enumerationvalueid = fm.factorytype \n");
    var1.Append("       INNER JOIN census_district cd \n");
    var1.Append("               ON cd.districtcode = fm.districtid \n");
    var1.Append("       INNER JOIN enumerationvalue ev \n");
    var1.Append("               ON ev.enumerationvalueid = cd.divisionid \n");
    var1.Append("WHERE  cd.langid = 1 \n");
    var1.Append("       AND tblpullsms.isactive = 1 \n");
    var1.Append("       AND CONVERT(varchar(10), tblpullsms.createddate, 120) = convert(varchar(10),GetDate(),120) \n");
    var1.Append("GROUP  BY fm.factoryname, \n");
    var1.Append("          cd.districtname, \n");
    var1.Append("          tblpullsms.code, \n");
    var1.Append("          tblpullsms.createddate, \n");
    var1.Append("          ev.enumerationvalue, \n");
    var1.Append("          ec.enumerationvalue, \n");
    var1.Append("          tblpullsms.mobileno, \n");
    var1.Append("          tblpullsms.crush, \n");
    var1.Append("          tblpullsms.prod, \n");
    var1.Append("          tblpullsms.rate, \n");
    var1.Append("          tblpullsms.recov,tblpullsms.ID, \n");
    var1.Append("          ev.enumerationvalue \n");
    var1.Append("ORDER  BY tblpullsms.createddate DESC ");

    String strdailyreportsms = string.Empty;
    SqlCommand cmd = new SqlCommand();
    strdailyreportsms = var1.ToString();
    cmd.CommandType = CommandType.Text;
   
    cmd.CommandText = strdailyreportsms;
    DataSet ds = new DataSet();
    ds = MOLDBAccess.ExecuteDataSet(cmd);

    if (ds.Tables[0].Rows.Count > 0)
    {
        //grdupload.DataSource = ds;
        grdupload.DataSource = ds.Tables[0];
        grdupload.DataBind();


    }
    else
    {
        grdupload.DataSource = null;
        grdupload.DataBind();
    }
}