Styles in ResourceDicitonary with Multiple DataTemplates not getting applied

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XAML

WPF

I am defining 4 different DataTemplates within a ResourceDicitonary. All of these DataTemplates have Lables and TextBoxes to which I want to apply a uniform Style from an external resource. This is how I am doing it and the Styles are not getting applied to Text boxes/labels. Am I doing sth wrong

<ResourceDictionary.MergedDictionaries>

    <ResourceDictionary Source="..\BaseStyles.xaml"/>
    <ResourceDictionary Source="..\Styles\Brushes.xaml"/>

<ResourceDictionary>

    <Style BasedOn="{StaticResource txtWidth50}" TargetType="TextBox"/>
    <Style BasedOn="{StaticResource lbStyle11}" TargetType="Label"/>

    <DataTemplate DataType= "{x:Type my:A}">
            <!--Have textboxes and labels-->
    </DataTemplate>

    <DataTemplate DataType="{x:Type my:B}">
            <!--Have textboxes and labels-->
    </DataTemplate>

    <DataTemplate DataType="{x:Type my:C}">
            <!--Have textboxes and labels-->
    </DataTemplate>

    <DataTemplate DataType="{x:Type my:D}">
            <!--Have textboxes and labels-->
    </DataTemplate>

</ResourceDictionary>

<ResourceDictionary.MergedDictionaries>