Datagrid row style

I'm having difficulty getting a datagrid to behave properly.

This style does not have any effect on the grid rows:

<Style TargetType="{x:Type DataGridRow}">
    <Style.Triggers>
        <Trigger Property="IsSelected" Value="True">
            <Setter Property="Background" Value="Brown" />
            <Setter Property="Foreground" Value="White" />
        </Trigger>

        <Trigger Property="IsSelected" Value="False">
            <Setter Property="Background" Value="White" />
            <Setter Property="Foreground" Value="Black" />
        </Trigger>
    </Style.Triggers>
</Style>

What am I doing wrong?