Simple SendMessage prob or killing a window

[Hack]

Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
Private Const WM_CLOSE = &H10
 
Private Sub cmdCloseApp_Click()
Dim CloseIt As Long
CloseIt = FindWindow(vbNullString, "Caption Of Window To Be Closed")
PostMessage CloseIt, WM_CLOSE, CLng(0), CLng(0)
End Sub