wpf datatrigger binding datacontext in textblock doesn't work - wpf

Question

I'm struggeling with binding a datatrigger to a textblock property. I have added a working Datatrigger example in the TextBox.
The issue is the TextBlock DataTrigger I can not get working. At startup IsNameActive has value 'false' and BackGround is PaleVioletRed, but it does not change when IsNameActive changes.
public bool IsNameActive
{
get => !string.IsNullOrEmpty(FirstName);
}
public string FirstName
{
get => _firstName;
set
{
if (value != _firstName)
{
_firstName = value;
OnPropertyChanged(FirstName);
OnPropertyChanged(IsNameActive);
}
}
}
<TextBox
Grid.Row="0"
Grid.Column="1"
Margin="15"
Text="{Binding UpdateSourceTrigger=PropertyChanged, Path=FirstName, ValidatesOnDataErrors=true, NotifyOnValidationError=true}">
<TextBox.Style>
<Style TargetType="TextBox">
<Setter Property="Background" Value="RosyBrown" />
<Style.Triggers>
<DataTrigger Binding="{Binding Text, RelativeSource={RelativeSource Self}}" Value="aa">
<Setter Property="Background" Value="DarkOliveGreen" />
</DataTrigger>
<DataTrigger Binding="{Binding Text, RelativeSource={RelativeSource Self}}" Value="">
<Setter Property="Background" Value="CornflowerBlue" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
<TextBlock
Grid.Row="2"
Grid.Column="1"
Margin="15"
Text="TextBlock with binding">
<TextBlock.Style>
<Style TargetType="TextBlock">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=DataContext.IsNameActive, RelativeSource={RelativeSource Self}, UpdateSourceTrigger=PropertyChanged}" Value="true">
<Setter Property="Background" Value="CornflowerBlue" />
</DataTrigger>
<DataTrigger Binding="{Binding Path=DataContext.IsNameActive, RelativeSource={RelativeSource Self}, UpdateSourceTrigger=PropertyChanged}" Value="false">
<Setter Property="Background" Value="PaleVioletRed" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>

Answer 1

As #Ash pointed out in the comment section, you need to wrap nameof around IsNameActive when you call OnPropertyChanged:
OnPropertyChanged(nameof(IsNameActive));