MRU菜单流利。丝带-无法将命令关联到ModelView

Fluent.Ribbon 图书馆。

但我不知道如何通过OpenCommand将这些项目连接起来

class MainWindowVM : NotifyingObject
{
    private ICommand openCommand;
    private ObservableCollection<String> recentFileNames = new ObservableCollection<string>() { "Bellerophon", "Athena" };
    public ICommand OpenCommand
    {
        get => openCommand;
    }
    public ObservableCollection<String> RecentFileNames
    {
        get => recentFileNames;
    }
}

Viewmodel将应用于RibbonWindow

<Window.DataContext>
    <vm:MainWindowVM />
</Window.DataContext>

我的按钮的当前状态是:

<Fluent:SplitButton Header="Open..." Size="Middle"
        Command="{Binding OpenCommand}"
        ItemsSource="{Binding Path=RecentFileNames}">
    <Fluent:SplitButton.Icon>
        <Image Source="Icons/folder-open-document.png" />
    </Fluent:SplitButton.Icon>
    <Fluent:SplitButton.LargeIcon>
        <Image Source="Icons/folder-open-document.png" />
    </Fluent:SplitButton.LargeIcon>
    <Fluent:SplitButton.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}"/>
        </DataTemplate>
    </Fluent:SplitButton.ItemTemplate>
    <Fluent:SplitButton.ItemContainerStyle>
        <Style TargetType="{x:Type Fluent:MenuItem}">
            <Setter Property="Command"
                Value="{Binding DataContext.OpenCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Fluent:MenuItem}, AncestorLevel=1}}" />
            <!--Setter Property="CommandParameter" Value="{}" /-->
        </Style>
    </Fluent:SplitButton.ItemContainerStyle>
</Fluent:SplitButton>

我把这段代码改编自另一个运行在普通菜单项上的SO问题。但我的命令不会被召唤。我知道我最终必须传递一个参数来区分不同的项,但我甚至不能让它运行普通命令。