Access level WPF

Question

I have a style file and I used animations in it. I want to put the name of the button on the page for (StopStoryboard) for (SourceName), but it gives an error

---

File Style :

<EventTrigger SourceName="Button_main" RoutedEvent="Mouse.MouseLeave">
                <StopStoryboard BeginStoryboardName="bsb1"/>
            </EventTrigger>
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Grid :

<Button x:Name="sb" x:FieldModifier="public"/>
            
        </Button

Answer 1

<EventTrigger SourceName="Button_main" RoutedEvent="Mouse.MouseLeave">
                <StopStoryboard BeginStoryboardName="bsb1"/>
            </EventTrigger>
------------------------------------------------------
Grid :

<Button x:Name="Button_main" x:FieldModifier="public"/>
            
        </Button