Why does the storyboard.target not get animated?

Question

I want to animate a stack panel on button click, the Button I click does animate while the StackPanel doesn't

this is in the button ControlTemplate

<EventTrigger RoutedEvent="Click">
    <BeginStoryboard>
        <Storyboard>
            <DoubleAnimation Storyboard.Target="{Binding ElementName=menus}"        
                Storyboard.TargetProperty="Width"
                From="0" To="1500"
                Duration="0:0:2" />
        </Storyboard>
    </BeginStoryboard>
</EventTrigger>

This is in the xaml

<StackPanel x:Name="menus" Orientation="Horizontal"
    VerticalAlignment="Bottom"
    HorizontalAlignment="Center"
    Margin="160 0 0 120">
        <Button Margin="30" Content="Open Account" Style="{StaticResource MenuButton}" />
        <Button Margin="30" Content="Instant Card Printing" Style="{StaticResource MenuButton}" />
        <Button Margin="30" Content="Banking Services" Style="{StaticResource MenuButton}" />
        <Button Margin="30" Content="Bill Payment" Style="{StaticResource MenuButton}" />
        <Button Margin="30" Content="Support" Style="{StaticResource MenuButton}" />
</StackPanel>

I want the stack panel to animate from left to right once the button is clicked

Answer 1

I'm not sure what about your code is causing your example to fail. There is probably something going on in the XAML that you didn't post. Below is a complete and self-contained example that functions exactly as you described:

<StackPanel>
    <Button Content="Clicky Button" Margin="10" HorizontalAlignment="Left">
        <Button.Triggers>
        <EventTrigger RoutedEvent="PreviewMouseDown">
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation Storyboard.Target="{Binding ElementName=menus}"        
                      Storyboard.TargetProperty="Width"
                      From="0" To="500"
                      Duration="0:0:2" />
                </Storyboard>
            </BeginStoryboard>
            </EventTrigger>
        </Button.Triggers>
    </Button>
    <StackPanel x:Name="menus" Orientation="Horizontal" Width="0"
                VerticalAlignment="Bottom" HorizontalAlignment="Center">
        <Button Content="Open Account" />
        <Button Content="Instant Card Printing" />
        <Button Content="Banking Services" />
        <Button Content="Bill Payment" />
        <Button Content="Support"/>
    </StackPanel>
</StackPanel>

When you click on 'Clicky Button' the StackPanel grows to a width of 500 over the course of 2 seconds.