asp.net - エラー: テーブル 0 が見つかりません

Question

 con.Open();
 SqlDataAdapter da4 = new SqlDataAdapter("select * from tblbooking where bookid =(select max(bookid) from tblbooking)", con);
 DataSet ds4 = new DataSet();
 pay = ds4.Tables[0].Rows[0]["costoftickets"].ToString();
 Label4.Text = "Amount to Pay : " + pay + " INR.";
 da4.Fill(ds4);
 DetailsView1.DataSource = ds4;
 DetailsView1.DataBind();
 con.Close();