DLL中使用定时器

#include <afx.h>
#include "dll.h"
#include "math.h"
#include "header.h"
#include "windows.h"

void CALLBACK T1(HWND hwnd, UINT uMsg, UINT idEvent, DWORD dwTime);::SetTimer(1, 0, 2000, T1);void CALLBACK T1(HWND hwnd, UINT uMsg, UINT idEvent, DWORD dwTime)
{
MessageBox(NULL,"定时器调用成功！","对话框",0);
}错误：error C2501: 'SetTimer' : missing storage-class or type specifiers我已经包含了windows.h。time.h试过，也不行！