Global style can't be overridden - wpf

Question

I have this defined in my app.xaml
<Style TargetType="{x:Type TextBlock}">
<Setter Property="FontSize" Value="12"></Setter>
<Setter Property="FontFamily" Value="Cailibri"></Setter>
</Style>
and this defined in Window1.xaml
<Style x:Key="BASE">
<Setter Property="Control.FontSize" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}, Path=MyFontSize}">
</Setter>
<Setter Property="Control.FontFamily" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}, Path=MyFontFamily}">
</Setter>
<Setter Property="Control.HorizontalAlignment" Value="Left">
</Setter>
</Style>
<Style TargetType="{x:Type TextBlock}" BasedOn="{StaticResource BASE}">
</Style>
<Style TargetType="lc:LayoutItem" BasedOn="{StaticResource BASE}">
<Setter Property="LabelStyle">
<Setter.Value>
<Style TargetType="lc:LayoutItemLabel" BasedOn="{StaticResource BASE}">
</Style>
</Setter.Value>
</Setter>
</Style>
<lc:LayoutControl x:Name="HeadLayout" lc:LayoutControl.CustomizationLabel="test" ItemInsertionPointIndicatorStyle="{StaticResource myInsertionPointIndicator}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
AllowNewItemsDuringCustomization="False" AllowAvailableItemsDuringCustomization="True" Orientation="Horizontal">
<lc:LayoutGroup Orientation="Vertical" View="Group" Margin="0,0,0,0" HorizontalAlignment="Stretch" VerticalAlignment="Top">
<lc:LayoutItem Label=" CDFEG " x:Name="StoreName" >
<TextBlock TextWrapping="Wrap" Text="ABCDEFG"/>
</lc:LayoutItem>
</lc:LayoutGroup>
</lc:LayoutControl>
when i change the fontsize or fontfamily property , it works fine when TextBlock isn't defined in app.xaml. I've searched this for a long time , but there's not quite a solution to me. any advice will help, thx.

Answer 1

It's been resolved, using DataTemplate.
<Style TargetType="lc:LayoutItem" x:Key="myLayoutItemStyle" BasedOn="{StaticResource BASE}">
<Setter Property="LabelTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}" >
<TextBlock.Style>
<Style BasedOn="{StaticResource BASE}">
</Style>
</TextBlock.Style>
</TextBlock>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
check it here, http://documentation.devexpress.com/#WPF/DevExpressXpfLayoutControlLayoutItem_LabelTemplatetopic.