I tried to create a XamTree with following xaml:

  <UserControl.Resources>
        <DataTemplate x:Key="ExpandedIcon">
            <Grid>
                <Image Source="open.png" Height="35" Width="24"/>
            </Grid>
        </DataTemplate>
        <DataTemplate x:Key="CollapsedIcon">
            <Grid>
                <Image Source="close.png" Height="35" Width="24"/>
            </Grid>
        </DataTemplate>
    </UserControl.Resources>
    <Grid x:Name="LayoutRoot" Background="White"  HorizontalAlignment="Stretch">
            <ig:XamTree ExpandedIconTemplate="{StaticResource ExpandedIcon}" CollapsedIconTemplate="{StaticResource CollapsedIcon}" >
            <ig:XamTree.HierarchicalItemTemplate>               
                    <ig:HierarchicalDataTemplate ItemsSource="{Binding Children}">
                        <ig:HierarchicalDataTemplate.ItemTemplate>
                            <DataTemplate>
                                <StackPanel Orientation="Horizontal">
                                    <TextBlock Text="{Binding Name}" Foreground="Gray" />
                                </StackPanel>
                            </DataTemplate>                           
                        </ig:HierarchicalDataTemplate.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <TextBlock Text="{Binding Name}" FontWeight="Bold"/>
                            </StackPanel>
                        </DataTemplate>
                    </ig:HierarchicalDataTemplate>
                </ig:XamTree.HierarchicalItemTemplate>
            </ig:XamTree>
        </Grid>

Data is loaded from database.  with about code, all tree nodes have same icon. I want to different level nodes have different icon. How to resolve this issue?