Charles Petzold

A couple WPF programmers have puzzled about this subject recently so maybe next time somebody has the problem they'll find this blog entry.

When setting Storyboard.TargetProperty to an attached property (such as Canvas.Left or Canvas.Top), put the fully-qualified property name in parentheses:

Storyboard.TargetProperty="(Canvas.Left)"

Here's a functional example:

<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
    <Ellipse Name="ellipse" Width="100" Height="100"
             Fill="Red" Stroke="Blue" StrokeThickness="10" />
    <Canvas.Triggers>
        <EventTrigger RoutedEvent="Canvas.Loaded">
            <BeginStoryboard>
                <Storyboard TargetName="ellipse"
                            RepeatBehavior="Forever">
                    <DoubleAnimation Storyboard.TargetProperty="(Canvas.Left)"
                                     From="100" To="800" Duration="0:0:3"
                                     AutoReverse="True" />
                    <DoubleAnimation Storyboard.TargetProperty="(Canvas.Top)"
                                     From="100" To="400" Duration="0:0:0.3"
                                     RepeatBehavior="10x"
                                     AutoReverse="True" />
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Canvas.Triggers>
</Canvas>