如何在Resources中通过ElementName绑定？

Question

它有效，但并非总是如此。

1. 作品。

MainWindow.xaml：

<Window x:Class="WpfApplication2.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApplication2"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<local:UserControl1></local:UserControl1></Window>

1. 作品。

MainWindow.xaml：

<UserControl x:Class="WpfApplication2.UserControl1"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:WpfApplication2"
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
    <Storyboard x:Key="OnMouseDown1">
        <DoubleAnimation Storyboard.TargetProperty="Width" Storyboard.TargetName="viewbox"
                         From="{Binding ElementName=viewbox, Path=ActualWidth}"
                         To="0"
                         Duration="0:0:1">
        </DoubleAnimation>
    </Storyboard>
</UserControl.Resources>
<Viewbox x:Name="viewbox">
    <Ellipse x:Name="ellipse" Width="100" Height="100" Fill="Red">
        <Ellipse.Triggers>
            <EventTrigger RoutedEvent="UIElement.MouseDown" SourceName="ellipse">
                <BeginStoryboard Storyboard="{StaticResource OnMouseDown1}"/>
            </EventTrigger>
        </Ellipse.Triggers>
    </Ellipse>
</Viewbox></UserControl>

UserControl1.xaml：

<Window x:Class="WpfApplication2.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApplication2"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<local:UserControl1></local:UserControl1></Window>

1. 不能工作。

MainWindow.xaml：

<UserControl x:Class="WpfApplication2.UserControl1"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:WpfApplication2"
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
    <Storyboard x:Key="OnMouseDown1">
        <DoubleAnimation Storyboard.TargetProperty="Width" Storyboard.TargetName="viewbox"
                         From="{Binding ElementName=viewbox, Path=ActualWidth}"
                         To="0"
                         Duration="0:0:1">
        </DoubleAnimation>
    </Storyboard>
</UserControl.Resources>
<UserControl.Triggers>
    <EventTrigger RoutedEvent="UIElement.MouseDown" SourceName="ellipse">
        <BeginStoryboard Storyboard="{StaticResource OnMouseDown1}"/>
    </EventTrigger>
</UserControl.Triggers>
<Viewbox x:Name="viewbox">
    <Ellipse x:Name="ellipse" Width="100" Height="100" Fill="Red"></Ellipse>
</Viewbox></UserControl>

UserControl1.xaml：

$('#calendar').fullCalendar('updateEvent', event);

例外：

  

未处理的类型＆＃39; System.Windows.Media.Animation.AnimationException＆＃39;发生在PresentationCore.dll中   附加信息：无法设置＆＃39;宽度＆＃39; “System.Windows.Controls.Viewbox”上的属性＆＃39;使用＆＃39; System.Windows.Media.Animation.DoubleAnimation＆＃39;。有关详细信息，请参阅内部异常。

如何让它发挥作用？