datarow to dataset in asp

DataTable dt = (DataTable)ViewState["tabData"];
DataRow[] dr = dt.Select("test_cd='899'");

DataSet dsnew = new DataSet();
DataTable dtnew = dt.Clone();
dtnew.Constraints.Clear();
DataRow drnew = dtnew.NewRow();

drnew.ItemArray = dr[0].ItemArray;
dtnew.Rows.Add(drnew);
dsnew.Tables.Add(dtnew);