My ItemContainerStyle works perfectly when a ListViewItem is added:

   <Style x:Key="ItemContStyle"
           TargetType="{x:Type ListViewItem}">
        <Style.Resources>
            <SolidColorBrush x:Key="lossBrush"
                             Color="Red" />
            <SolidColorBrush x:Key="newPartNo"
                             Color="LightGreen" />
            <SolidColorBrush x:Key="noSupplier"
                             Color="Yellow" />
            <Orders:OrderItemStatusConverter x:Key="OrderItemConverter" />
        </Style.Resources>
        <Style.Triggers>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=DataContext, Converter={StaticResource OrderItemConverter}}"
                         Value="-1">
                <Setter Property="Background"
                        Value="{StaticResource lossBrush}" />
            </DataTrigger>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self},Path=DataContext, Converter={StaticResource OrderItemConverter}}"
                         Value="-2">
                <Setter Property="Background"
                        Value="{StaticResource newPartNo}" />
            </DataTrigger>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self},Path=DataContext, Converter={StaticResource OrderItemConverter}}"
                         Value="-3">
                <Setter Property="Background"
                        Value="{StaticResource noSupplier}" />
            </DataTrigger>
        </Style.Triggers>
    </Style>

However when the source item changes, the trigger is not fired and the background colour is not what I expect.

How can I make the trigger fire?