It may be a custom-drawn button, not a standard button. In this case there might even be no tools to identify and script this UI element.
Another possibility is that the application is build with WPF (Windows Presentation Foundation). It a new UI toolkit by microsoft, instead of the classic user32 WinAPI objects (windows with ID, window Class, etc.) employed by classic Windows applications (btw, ActiveX, Visual Basic would mostly use classic WinAPI), and most of tools expect (like Spy++ and various UI test automation toolkits).