what's wrong with this code?

[.paul.]

this is a c++ example that i found on the internet + i'm trying to modify. it compiles successfully but when i try to use the functions in a vb.net application it causes a System.EntryPointNotFoundException error:

// hookDll.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"

#pragma data_seg("Shared")		//these variables will be shared among all processes to which this dll is linked
HHOOK hkKey = NULL;				
HINSTANCE hInstHookDll=NULL;
HWND parentHWnd = NULL;
#pragma data_seg()

#pragma comment(linker,"/section:Shared,rws")


BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved
					 )
{
	switch(ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		hInstHookDll = (HINSTANCE)hModule;		//we initialize our variable with the value that is passed to us
		break;
	}
    return TRUE;
}

LRESULT CALLBACK procCharMsg(int nCode,WPARAM wParam, LPARAM lParam)		//this is the hook procedure
{
	MSG *msg;																//a pointer to hold the MSG structure that is passed as lParam
	if(nCode >=0 && nCode == HC_ACTION)										//if nCode is less than 0 or nCode is not HC_ACTION we will call CallNextHookEx
	{
		msg=(MSG *)lParam;													//lParam contains pointer to MSG structure.
		if(msg->message==WM_CTLCOLOREDIT)									//we handle only WM_CTLCOLOREDIT messages
		{
			SendMessage(parentHWnd,WM_CTLCOLOREDIT,0,0);					//passing this message to parent application
		}
	}
	return CallNextHookEx(hkKey,nCode,wParam,lParam);						
}

//set the hook
//how can i change this to a function that returns hWnd if it hooks successfully?
HWND __stdcall SetHook(HWND hWnd)
{
	if(hkKey == NULL)
		hkKey = SetWindowsHookEx(WH_GETMESSAGE,procCharMsg,hInstHookDll,0);
	    parentHWnd = hWnd;
		return parentHWnd;
}

//remove the hook
void __stdcall RemoveHook()
{
	if(hkKey !=NULL)
		UnhookWindowsHookEx(hkKey);
	    hkKey = NULL;
}

this is the .def file:

EXPORTS
SetHook @2
RemoveHook @3

+ this is how i'm declaring them in vb.net:

Declare Function SetHook Lib "hookDll.dll" (ByVal hWnd As IntPtr) As IntPtr
Declare Sub RemoveHook Lib "hookDll.dll" ()

what am i doing wrong?