Caliburn微型键盘快捷键不工作

给定以下XAML:

<UserControl x:Class="Solution.Views.SomeView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
    xmlns:cm="http://www.caliburnproject.org"
    cm:Message.Attach="[Key F11] = [ToggleFullScreen]">
    <Grid>
        <ToolBar DockPanel.Dock="Top" Margin="0">
            <xctk:IconButton Style="{StaticResource ToolBarButton}" ToolTip="Full Screen (F11)"
                cm:Message.Attach="ToggleFullScreen">
                <Image Style="{StaticResource ToolBarButtonImage}" Source="pack://application:,,,/Resources/Img/Full_Screen32.png"/>
            </xctk:IconButton>
        </ToolBar>
    </Grid>
</UserControl>

ToggleFullScreen 方法,但按钮点击将。将[键F11]更改为[手势Alt+F]或[手势F11]也不起作用。。。