Property Grid - change Cell Background based on Cell Value (MVVM)

Good Morning all

I need to change the Propertygrids Cell Background Color based on the Cells Value.

I got this Object bound to the DataObject of the Grid:

    public class LogItemProperty
    {
        public LogItemProperty() { }

        [Category("Entry")]
        [DisplayName("Id")]
        [Description("Id of the Log-Record")]
        public int Id { get; set; }

        [Category("Entry")]
        [DisplayName("Level")]
        [Description("Error Level of the Log-Record")]
        public string Level { get; set; }

...

The View Model looks like that

	private LogItemProperty _selectedLogItemProperty;
	public LogItemProperty SelectedLogItemProperty
	{
		get => _selectedLogItemProperty;
		set => _selectedLogItemProperty = value;
	}

The Property Grid is configured like this

                <grids:PropertyGrid x:Name="propGrid" IsSummaryVisible="True"
                                    gridseditors:BuiltinPropertyEditors.IsEnabled="False"
                                    CanClearDataObjectOnUnload="True"
                                    DataObject="{Binding Path=SelectedLogItemProperty}"  Grid.Column="0" Grid.Row="0" Grid.RowSpan="2"
                                    IsReadOnly="True" />

The Grid is filled with the correct Data!

Now I tried to create a Style (to be honest,my first one):

<Style  x:Key="LogItemPropertyGridRowStyle"
        TargetType="{x:Type grids:PropertyGridItem}">
        <Style.Triggers>

            <!-- Warn -->
            <DataTrigger
                Binding="{Binding Level, Mode=OneWay, RelativeSource={RelativeSource Self}, PresentationTraceSources.TraceLevel=High}"
                Value="WARN">
                <Setter
                    Property="Background"
                    Value="{StaticResource WarnLevelColor}" />
            </DataTrigger>

            <!-- Error -->
            <DataTrigger
                Binding="{Binding Level, Mode=OneWay, RelativeSource={RelativeSource Self}, PresentationTraceSources.TraceLevel=High}"
                Value="ERROR">
                <Setter
                    Property="Background"
                    Value="{StaticResource ErrorLevelColor}" />
            </DataTrigger>

            <!-- Fatal -->
            <DataTrigger
                Binding="{Binding Level, Mode=OneWay, RelativeSource={RelativeSource Self}, PresentationTraceSources.TraceLevel=High}"
                Value="FATAL">
                <Setter
                    Property="Background"
                    Value="{StaticResource FatalLevelColor}" />
            </DataTrigger>

        </Style.Triggers>
</Style>

But nothing happend :-(

Any help is welcome!

Kind Regards
Peter