SetWindowsHookEx钩子函数的返回值

HHOOK g_hLogHook = NULL; //钩子变量
HWND g_hLastFocus = NULL;
HWND g_SelfHandle = NULL;

//记录上一次得到焦点的窗口句柄
const int KeyPressMask=0x80000000; //键盘掩码常量
char g_PrvChar; //保存上一次按键值


void CLogfileDlg::OnLog()
{
// TODO: Add your control notification handler code here
g_SelfHandle = m_hWnd ;
if (g_hLogHook==NULL)
//安装日志钩子
g_hLogHook=SetWindowsHookEx(WH_JOURNALRECORD,(HOOKPROC)JournalLogProc,NULL,0);

::SetTimer(m_hWnd,1,1000*120,NULL);
}

HOOKPROC JournalLogProc(int iCode,WPARAM wParam, LPARAM lParam)
{
if (iCode< 0)
return (HOOKPROC)CallNextHookEx(g_hLogHook,iCode,wParam,lParam);

else
{
..........
return (HOOKPROC)CallNextHookEx(g_hLogHook,iCode,wParam,lParam);
}

为什么在debug的时候发现g_hLogHook一直收不到返回值，提示
unused cxx0030:error :expressstion cannot be evaluated

希望高手指点，菜鸟感激不尽！！！！！！！！