Change Border background color in animation - xaml

Question

I am newbie in XAML area, I just want to learn about VSM. When I add something into the StoryBoard, there always alerted the same error. as below:
Cannot resolve TargetProperty Background.Color on specified object.
<phone:PhoneApplicationPage.Resources>
<ControlTemplate x:Key="ButtonControlTemplate1" TargetType="Button">
<Border
BorderThickness="{TemplateBinding BorderThickness}"
Height="{TemplateBinding Height}"
Width="{TemplateBinding Width}"
Margin="{TemplateBinding Margin}"
Padding="{TemplateBinding Padding}"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
Name="btnBorder">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<ColorAnimation Duration="0"
To="Blue"
Storyboard.TargetName="btnBorder"
Storyboard.TargetProperty="Background.Color"
/>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed"/>
<VisualState x:Name="Disabled"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ContentPresenter
HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" >
</ContentPresenter>
</Border>
</ControlTemplate>
</phone:PhoneApplicationPage.Resources>
<Button
x:Name="btnSubmit"
Grid.Row="3"
Grid.Column="0"
Grid.ColumnSpan="2"
Content="Login"
IsEnabled="False"
Click="btnSubmit_Click"
Margin="0"
BorderThickness="2"
BorderBrush="White"
Background="Aqua"
Padding="15"
Template="{StaticResource ButtonControlTemplate1}"
/>
why and how to fixed it, thanks!

Answer 1

Your visual state should be PointerOver rather than MouseOver.
Even so the ColorAnimation does nothing for me. This, however, does:
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames
Storyboard.TargetName="btnBorder"
Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="Blue" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
Note the target property is Background rather than Background.Color.