Windows 8.1 phone app ExtendedListView.GroupStyle not working

Question

I am using ExtendedListView in my application as I need pool to refresh option.

I have installed ExtendedListview 0.0.5.5 by installing with nuget package: Install-Package ExtendedListview

Now I also want a sticky header in my listview.

So I am able to do it in Simple List view by below code.

<ListView IsHoldingEnabled="True"
    ItemsSource="{Binding Source={StaticResource AddressGroups}}"
    ItemTemplate="{StaticResource AddrBookItemTemplate}"
    ContinuumNavigationTransitionInfo.ExitElementContainer="True">
    <ListView.GroupStyle>
        <GroupStyle HidesIfEmpty="True" HeaderTemplate="{StaticResource AddrBookGroupHeaderTemplate}"/>
    </ListView.GroupStyle>
</ListView>

But same thing is not working in ExtendedListView.

<ctrl:ExtendedListView IsHoldingEnabled="True"
        ItemsSource="{Binding Source={StaticResource AddressGroups}}"
        ItemTemplate="{StaticResource AddrBookItemTemplate}"
        ContinuumNavigationTransitionInfo.ExitElementContainer="True"  >
    <ctrl:ExtendedListView.GroupStyle>
        <GroupStyle HeaderTemplate="{StaticResource AddrBookGroupHeaderTemplate}" />
    </ctrl:ExtendedListView.GroupStyle>
</ctrl:ExtendedListView>

I have used same HeaderTemplate in both code as below:

<DataTemplate x:Key="AddrBookGroupHeaderTemplate">
    <Border Background="Transparent" Padding="5">
        <Border Background="Red" BorderBrush="Red" BorderThickness="2" Width="80" 
                Height="62" Margin="0,0,18,0" HorizontalAlignment="Left">
            <TextBlock Text="{Binding Key}" Foreground="White" FontSize="48" Padding="6" 
                        HorizontalAlignment="Left" VerticalAlignment="Center"/>
        </Border>
    </Border>
</DataTemplate>

Please guide me ASAP.

Thanks in advance.