求助:我的 DLL ，在 delphi 中调用有错啊

TEST3

test3.h
#ifdef SENDCARD_EXPORTS
#define SENDCARD_API extern "C" __declspec(dllexport)
#else
#define SENDCARD_API extern "C" __declspec(dllimport)
#endif


#define ON 1
#define OFF 0
#define OK 0
#define FAIL 1
#define DATA 0
#define BufferSize 50
#define MCR1 4
#define MSR 6
#define LSR1 5
#define B0 0x01
#define B7 0x80
#define OFF 0
#define SPACE ' '
#define TRUE 1
#define FALSE 0



extern "C" _declspec(dllexport) int sum(int a,int b);//


test3.cpp
#include "stdafx.h"
#include "math.h"
#include "test3.h"
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
return TRUE;
}


extern "C" _declspec(dllexport) int sum(int a, int b)
{
return a+b;
}

编译生成了 test3.dll


我在 delphi 里:

unit Unit2;

interface

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

Function sum(i:integer; j:integer):integer;stdcall; //

implementation

Function sum(i:integer; j:integer):integer;external 'test3.dll'; //

end.



unit Unit1;

interface

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

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

var
Form1: TForm1;

implementation
uses
Unit2;



{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
m : integer;
begin
m := sum(20,30);
edit1.Text := inttostr(m);
end;

end.


可是按 Button1 出现内存地址错误

是不是
extern "C" _declspec(dllexport) int sum(int a,int b);//
应该改为
extern "C" _stdcall int sum(int a,int b);//
啊

如果是这样的话
#ifdef SENDCARD_EXPORTS
#define SENDCARD_API extern "C" __declspec(dllexport)
#else
#define SENDCARD_API extern "C" __declspec(dllimport)
#endif

应该改为什么呢？
谢谢！


我把
extern "C" _declspec(dllexport) int sum(int a, int b)
改为了 extern "C" int _stdcall sum(int a, int b)

也不行