C-Funktions-Aufruf SetText(char* szLine); nach Delphi

[TERWI]

Bescheid...
Positiv-Meldung: Ich hab meinen Text auf dem Display
Das ABER:
Wie ich oben schon sagte, führt der Aufruf der INIT-Funktion mit stdcall zur einer Access-Violation an Adresse 00000000.
Das hatte mich bisher davon abgehalten, es auf dem HTPC zu testen. Habe ich aber nun doch einfach mal gemacht....
Mein Label1 gibt mir OK zurück und der Text kommt. Den kann ich auch so oft ändern wie ich lustig bin - keine weiteren Fehler.
Auch Programm beenden (UNINIT) gibt kein Gemaule.
Was ist nun wieder verkehrt ?
Hier mal der kurze Quelltext zu Ansicht:

Delphi-Quellcode:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Button2: TButton;
    Label1: TLabel;
    Label2: TLabel;
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormShow(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  SGVFDDLL = 'SG_VFD.dll';

// used Function from SG_VFD.dll
function  VFD_Init(vfdType, dummy : integer) : bool; stdcall; external SGVFDDLL name 'iMONVFD_Init';
procedure VFD_Uninit(); stdcall; external SGVFDDLL name 'iMONVFD_Uninit';
function  VFD_IsInited() : bool; stdcall; external SGVFDDLL name 'iMONVFD_IsInited';
function  VFD_SetText(TXT1, TXT2 : PChar) : bool; stdcall; external SGVFDDLL name 'iMONVFD_SetText';
function  VFD_SetEQ(EQdata : array of integer) : bool; stdcall; external SGVFDDLL name 'iMONVFD_SetEQ';

{
TDUMP -ee SG_VFD.DLL             
EXPORT ord:0001='iMONVFD_CheckDign'
EXPORT ord:0002='iMONVFD_Init'
EXPORT ord:0003='iMONVFD_IsInited'
EXPORT ord:0004='iMONVFD_SetAlarmOFF'
EXPORT ord:0005='iMONVFD_SetAlarmON'
EXPORT ord:0006='iMONVFD_SetAlarmON_Abs'
EXPORT ord:0007='iMONVFD_SetEQ'
EXPORT ord:0008='iMONVFD_SetText'
EXPORT ord:0009='iMONVFD_Uninit'
///////////////////////////////////////////////
//   Open VFD driver and initialize parameters.
//   Call this method, when application starts.
//   Return value informs driver is open or not
bfdType = 4 !
IMONVFD_API bool iMONVFD_Init(int vfdType, int resevered=0);

///////////////////////////////////////////////
//   Close VFD driver.
//   Call this method, when application destroyed.
IMONVFD_API void iMONVFD_Uninit(void);

///////////////////////////////////////////////
//   Check if VFD driver is opened.
IMONVFD_API bool iMONVFD_IsInited(void);

///////////////////////////////////////////////
//   Send text data to VFD. VFD supports only English character set.
IMONVFD_API bool iMONVFD_SetText(char* szFirstLine, char* szSecondLine);

///////////////////////////////////////////////
//   Send EQ data to VFD.
//   Total 16band, each band ranges from 0 to 100
//  make EQ data with integer array.
EQValue : array[0..15] of integer !
IMONVFD_API bool iMONVFD_SetEQ(int* arEQValue);
}


procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  VFD_Uninit;
end;

procedure TForm1.FormShow(Sender: TObject);
begin
  if VFD_Init(4, 0) then
    label1.Caption := 'Init OK'
  else
    label1.Caption := 'Init failed';
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if VFD_SetText(PChar(Edit1.Text), PChar(Edit2.Text)) then
    label2.Caption := 'Text OK'
  else
    label2.Caption := 'Text failed';
end;

end.