WCF DataGrid列的自动换行

<DataGridTextColumn Header="测试" Width="2*" Binding="{Binding TestValue}">
      <DataGridTextColumn.ElementStyle>
               <Style TargetType="TextBlock">
                        <Setter Property="TextWrapping" Value="Wrap" />
                        <Setter Property="Height" Value="auto" />
               </Style>
       </DataGridTextColumn.ElementStyle>
</DataGridTextColumn>