Register an App with windows

Simple thing, but I can't get it to work! I'm trying to register my main
application with windows, so that a small mini (launcher) application can
find mine using FindWindow. My mini application simply has Sleep(100) inside
a "while (FindWindow(_T("CircaApp")) == 0)" loop, but it never finds my main
application (loops forever). My main application has the following code in
its InitInstance (I lifted this from an online example somewhere):

 // Register the class, so that FindWindow can find us.
 WNDCLASS wndcls;
 memset(&wndcls, 0, sizeof(WNDCLASS)); // start with NULL defaults
 wndcls.style = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
 wndcls.lpfnWndProc = ::DefWindowProc;
 wndcls.hInstance = AfxGetInstanceHandle();
 wndcls.hIcon = LoadIcon(IDR_MAINFRAME); // or load a different icon
 wndcls.hCursor = LoadCursor( IDC_ARROW );
 wndcls.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
 wndcls.lpszMenuName = NULL;
 // Specify your own class name for using FindWindow later
 wndcls.lpszClassName = _T("CircaApp");

 // Register the new class and exit if it fails
 if(!AfxRegisterClass(&wndcls))
 {
  TRACE("Circa Class Registration Failed\n");
  return false;
 }

Can anyone spot where I'm going wrong? Am I missing something else? Is there
a shorter way of doing this? Why doesn't FindWindow find my App?
Thanks,
GT