CLOB Oracle fetch problem

Problem occurs when reading CLOB data within Delphi6 client application over
ADO / OleDB from an Oracle 9.2 database.
Data ist truncated e.g. to 64 KB (original size in Database ~ 123 KB).
Problem occurs only on some CLOB fields; may depend on content.

On same Client PC I can read same CLOB field with Delphi App. over Borland
Database Engine without a problem.

The odd thing is: When I read the same data field from a VisualBasic
application over ADO/OleDB (same connection string etc.) it works fine.
-> probably it has to do something with AdoExpress components

Can anyone help? Thanks in advance.

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Sample Code:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, adodb, dbtables;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    Database: TAdoConnection;
    qry: tadodataset;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  Temp: TStringList;
begin
  Temp := TStringList.Create;
  Database := TAdoConnection.Create(self);
  qry := TAdoDataset.Create(self);
  try
    // Connecting to Database
    Database.connectionstring := 'Provider=OraOLEDB.Oracle.1;Persist
Security Info=True;Data Source=PXDEMOORACLE;User
ID=phoenix;password=phoenix';
    Database.LoginPrompt:= False;
    Database.Connected:= True;
    // Dataset preparation
    qry.connection := Database;
    qry.cursortype := ctopenforwardonly;
    qry.cursorlocation := cluseclient;
    qry.autocalcfields := false;
    qry.EnableBCD := false;
    qry.commandtype := cmdtext;
    // Export to File
    qry.ParamCheck := False;
    qry.commandtext := format('select TEXT from APPMEMO where textid = %s',
[Edit1.Text]);
    qry.open;
    Temp.Text := qry.fieldbyname('text').asstring;
    Temp.SaveToFile('c:\temp\myfile.rtf');
  finally
    Session.DropConnections;
    Database.Connected:= False;
    Temp.Free;
    Database.Free;
    Qry.Free;
  end;
end;

end.