how to close an external application in a Borland C++ application

Hi all,

I want to close one external application in the other application, I develop the application with Borland C++ Builder. Here is the code I am using:
    HWND HWndCls;
    HWndCls=  Winprocs->FindWindow(nil, "cp801");
    if (HWndCls)
        SendMessage(HWndCls, WM_CLOSE, 0, 0);
But, when I compile it ,  error as "Undefined symbol 'Winprocs'" and
"Undefind symbol 'nil'" were reported. What's wrong? Is there some head-file I should include?

Thanks for telling me why?


tod.