How to get the control in resource when I show the chart using mvvm binding?

[PEIYANG]

in this sample http://localhost:6519/Default.aspx#Chart/SimpleFiltering,I want to get the control called checkbox1,but I cant get it with this.checkbox1,How to get the checkbox1??
  <UserControl.Resources>  
        <example:ExampleViewModel x:Key="ViewModel" />
        <Style x:Key="CustomLegendItemStyle" TargetType="charting:ChartLegendItem">  
            <Setter Property="Foreground" Value="Black" />
            <Setter Property="Template" >
                <Setter.Value>
                    <ControlTemplate TargetType="charting:ChartLegendItem">
                        <Grid x:Name="PART_MainContainer" HorizontalAlignment="Stretch" VerticalAlignment="Top" Margin="0,0,5,0">
                            <Path x:Name="PART_LegendItemMarker"
                                  Height="20"
                                  Width="100"
                                  Style="{TemplateBinding ItemStyle}"
                                  Stretch="Fill">
                                <Path.Data>
                                    <PathGeometry x:Name="PART_ItemMarkerGeometry" />
                                </Path.Data>
                            </Path>
                            <CheckBox IsChecked="True"  x:Name="checkbox1"
                                      VerticalAlignment="Center"
                                      Margin="2,0"
                                      Content="{TemplateBinding Label}"
                                      Foreground="{TemplateBinding Foreground}"
                                      Command="{Binding Path=ChangeSeriesVisibilityCommand, Source={StaticResource ViewModel}}"
                                      CommandParameter="{TemplateBinding Label}"
                                      />
                    </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>
 

[Petar Kirov]

Hello Peiyang,

  I suggest that you review the msdn documentation and more specifically this topic where it is shown how to access control-template generated elements.
Please note that this is a general question which is not directly related to our controls and the implementation of this code is out of our support scope.
If you have any more frustrations/questions on this - please ask them in the official Microsoft Silverlight forums or in StackOverflow.
 
Kind regards,
Petar Kirov
the Telerik team