I am trying to hide a label based on its value = N/A as passed into the tag. Does not seem to work any advice?

<Grid>
<Grid.Resources>

<Style TargetType="{x:Type Label}" x:Key="LabelTextStyle">
<Style.Triggers>
<Trigger Property="Tag" Value="N/A">
<Setter Property="Visibility" Value="Hidden"/>
<Setter Property="Background" Value="Blue"/>
<Setter Property="FontFamily" Value="Trebuchet MS"/>
<Setter Property="FontSize" Value="18"/>
</Trigger>
</Style.Triggers>
</Style>
</Grid.Resources>

<Label Style="{StaticResource LabelTextStyle}" FontSize="14" Tag="{Binding Path=lblCOO}" FontWeight="Bold" Foreground="#FFF9F7F7" Margin="23,9,59,36" Name="lblCOO" Grid.Column="3" Grid.Row="1"></Label>
</Grid>