编写Timer函数后自行添加映射ON_WM_TIMER()后出现下面问题

请大哥们帮小弟解决一下咯，新手~
1>c:\documents and settings\administrator\桌面\text\text100\text100\text100dlg.cpp(75) : error C2039: “OnTime”: 不是“Ctext100Dlg”的成员
1>        c:\documents and settings\administrator\桌面\text\text100\text100\text100dlg.h(10) : 参见“Ctext100Dlg”的声明
1>c:\documents and settings\administrator\桌面\text\text100\text100\text100dlg.cpp(75) : error C2065: “OnTime”: 未声明的标识符
下面是代码：
BEGIN_MESSAGE_MAP(Ctext100Dlg, CDialog)
    ON_WM_SYSCOMMAND()
    ON_WM_PAINT()
    ON_WM_QUERYDRAGICON()
    //}}AFX_MSG_MAP
    ON_BN_CLICKED(IDC_BUTTON1, &Ctext100Dlg::OnBnClickedButton1)
    ON_BN_CLICKED(IDC_BUTTON2, &Ctext100Dlg::OnBnClickedButton2)
    ON_WM_TIMER()///////////////////此处出错
    ON_BN_CLICKED(IDC_BUTTON3, &Ctext100Dlg::OnBnClickedButton3)
END_MESSAGE_MAP()