动画对象不能用于动画属性“BorderThickness”，因为它是不兼容的类型

“System.Windows.Media.Animation.DoubleAnimation”动画对象不能用于动画属性“BorderThickness”，因为它是不兼容的类型“System.Windows.Thickness”。

遇到一个奇怪的问题：为一个自定义的控件（继承自Button）设置ControlTemplate，如果设置
ControlTemplate的TargetType="{x:Type ButtonBase}"，下面的动画就会抛出异常，如果不
设置TargetType="{x:Type ButtonBase}"，ControlTemplate的设置就无效。求众位指点。

<Style TargetType="{x:Type local:ImageButton}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ButtonBase}">
                    <Border x:Name="border" BorderBrush="Blue" BorderThickness="0">
                        <ContentPresenter/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <EventTrigger RoutedEvent="MouseEnter">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation To="0.5" Duration="0:0:1" AutoReverse="False"
                                            Storyboard.TargetName="border"
                                            Storyboard.TargetProperty="(Border.BorderThickness)"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                        <EventTrigger RoutedEvent="MouseLeave">
                            <BeginStoryboard> 
 
                                <Storyboard>
                                    <DoubleAnimation To="0" Duration="0:0:1" AutoReverse="False"
                                            Storyboard.TargetName="border"
                                            Storyboard.TargetProperty="(Border.BorderThickness)"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

[解决办法]
DoubleAnimation 真的可以用于 BorderThickness 吗？

BorderThickness 是 Thickness 结构体。。