BasedOn DataTriggers not Activating
===

I created a base style for my navigation menu.  I want to change certain elements such as label content and icons based on a particular style while keeping the hover/click effects standard for all navigation items.

Here's my base XAML:

    <Style x:Key="BaseNavigationStyle">
         <Setter Property="Control.Cursor" Value="Hand"/>
         <Setter Property="Control.Padding" Value="0,6,0,6"/>
         <Setter Property="Control.Background" Value="{StaticResource NavigationItemBackgroundColorBrush}"/>
         <Style.Triggers>
              <DataTrigger Binding="{Binding Path=IsMouseOver, RelativeSource={RelativeSource Self}}" Value="True">
                   <DataTrigger.ExitActions>
                        <BeginStoryboard Storyboard="{StaticResource NavigationItemBackgroundNormal}"/>
                   </DataTrigger.ExitActions>
                   <DataTrigger.EnterActions>
                        <BeginStoryboard Storyboard="{StaticResource NavigationItemBackgroundHover}"/>
                   </DataTrigger.EnterActions>
              </DataTrigger>
         </Style.Triggers>       
    </Style>

Here's my XAML for a Navigation Item:

    <Style x:Key="ValidationNavigationStyle" BasedOn="{StaticResource BaseNavigationStyle}">
         <Setter Property="Navigation:NavigationUserControl.Image">
              <Setter.Value>
                   <BitmapImage UriSource="Assets/Navigation/validation.png"/>
              </Setter.Value>
         </Setter>
         <Setter Property="Navigation:NavigationUserControl.Label" Value="Validation"/>
    </Style>

Any ideas on why my all of the Setters (Cursor, Padding, Background) ARE being set but the MouseOver trigger is not working?

***Side Note:*** If I cut/paste the trigger into the `ValidationNavigationStyle`, it will work as expected.  I have a hunch that it has something to do with the RelativeSource binding but I can't quite figure out what it is.  