WPF程序。StackPanel中加入多個自定義控件Item。想用動畫把其中壹個Item的高度調至0，運行時出錯。求指導

在Window.Resources裏加

<Storyboard x:Key="Storyboard1">

<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Height)" Storyboard.TargetName="btn">

<EasingDoubleKeyFrame KeyTime="0:0:1" Value="0"/>

</DoubleAnimationUsingKeyFrames>

</Storyboard>

在Window.Triggers裏加

<EventTrigger RoutedEvent="FrameworkElement.Loaded">

<BeginStoryboard Storyboard="{StaticResource Storyboard1}"/>

</EventTrigger>

XAML代碼：

<StackPanel Orientation="Horizontal">

<Button Width="50" Height="50"/>

<Button Width="50" Height="50"/>

<Button x:Name="btn" Width="50" Height="50"/>

<Button Width="50" Height="50"/>

<Button Width="50" Height="50"/>

</StackPanel>