Error C2491: "ADD": the definition of DllImport function is not allowed

Beginner DLL, first record the problem, superficial understanding
win2003+vs2003
Code:
Include <iostream>
#include "DLLTutorial.h"

#define? Dll_export
extern "C"
{
Decldir int Add (int a, int b)
{
return a+b;
}

Decldir void Function (void)
{
std::cout<< "DLL called!" <<std::endl;
}
};

Problem:
Compiling ...
DLLTutorial.cpp
F:\hbj\112\112\DLLTutorial.cpp (9): Error C2491: "ADD": the definition of DllImport function is not allowed
F:\hbj\112\112\DLLTutorial.cpp: Error C2491: "function": the definition of DllImport functions is not allowed

Solve:
Include <iostream>
#include "DLLTutorial.h"

#define? Dll_export
The order is reversed,
should read:
#define? Dll_export
#include <iostream>
#include "DLLTutorial.h"

extern "C"
{
Decldir int Add (int a, int b)
{
return a+b;
}

Decldir void Function (void)
{
std::cout<< "DLL called!" <<std::endl;
}
};