WindowsElement Elements not found on a Windows WPF Application

Hi Gui
I have a Windows WPF Application.
My simple test that clicks on a Button Fails.
I noticed that the collection that return FindElementsByClassName is empty. The ClassName is Button, or Grid ecc…
If I analize the application with Inspector.exe, its return correct values:

RuntimeId: [7.178C.2AF1A58]
AutomationId: “ButOpenCommAppium”
FrameworkId: “WPF”
ClassName: “Button”

If I run the test on an other simple WPF application, its works fine

Thanks so much