Automation.AddAutomationEvent and WinForms

I've been playing around with the UI Automation API and I found that

the Invoke automation event does not work for WinForms applications.

I'm running Vista Beta 2 with VS .NET 2005. The WinForms app as well as

the app using UI Automation are both built using VS .NET 2005. The

WinForms app is a simple app with a button and a textbox. Clicking the

button does not trigger the Invoke event.

I've tried TreeScope.Element and TreeScope.Descendant in

AddAutomationEvent, neither of them works. It does work fine for Win32

apps though(I used Notepad as the sample).

I also noticed that even UISpy doesn't detect the Invoke events

(button clicks, for example) for Winforms applications. Is this a known

bug?