ASP.NET调用Oracle存储过程有关问题

using (OracleCommand Cmd = new OracleCommand("QueryPagedTable", Conn))            {                Cmd.CommandType = CommandType.StoredProcedure;                Cmd.Parameters.Add("PageSize", OracleType.Int32).Value = PageSize;                Cmd.Parameters.Add("PageNo", OracleType.Int32).Value = PageNo;                Cmd.Parameters.Add("Table_", OracleType.VarChar, 50).Value = Table;                Cmd.Parameters.Add("Filter", OracleType.VarChar, 1000).Value = Filter;                Cmd.Parameters.Add("Order_", OracleType.VarChar, 500).Value = Order == null ? "" : Order; ;                Cmd.Parameters["Order_"].Direction = ParameterDirection.Output;                OracleDataAdapter ad = new OracleDataAdapter(Cmd);                try                {                    if (Conn.State != ConnectionState.Open)                    {                        Conn.Open();                        OpenedHere = true;                    }                    ad.Fill(ds);                }                catch                {                    return null;                }                finally                {                    if (OpenedHere) if (Conn.State == ConnectionState.Open) Conn.Close();                }            }