Assign an event to an WPF control created via Datatemplate - wpf

Question

Using powershell, I have a WPF treeview control, where I used a data template to populate. Here is the example :
https://i.stack.imgur.com/FFMQN.png
My current problem is that I'm not able to register a CLICK event for the controls that are created via DATATEMPLATE. Actually $window.Findname does not find the control, if it has been created via datatemplate.
If I add a simple button via editing XAML code or creating the control during runtime, the FINDNAME or the variable attached to the control works well. and I can register click event.
But if the control is created via datatemplate, FINDNAME simply does not work.
Any suggestions ?
PS: Here is the powershell code WPF embeded :
Cls
Add-Type -Assembly PresentationFramework
Add-Type -Assembly PresentationCore
Function btnReload_click
{
Write-Host $this.name
}
$btnReload_click=({
$MyItemsListProperty = #(New-Object PSObject -Property #{Title='New guy in the town';icon="C:\temp\computer.png";Reloadbtn="Visible";spLoading="Hidden"})
$myDATA.Add($MyItemsListProperty)
$treeView.ItemsSource = $myDATA
})
[xml]$xaml = #"
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Threaded WPF Explorer" Height="840" Width="350" Icon="C:\temp\Computer.png" WindowStartupLocation="CenterScreen" >
<Grid>
<TreeView x:Name="foldersTree">
<TreeView.Resources>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="HeaderTemplate">
<Setter.Value>
<DataTemplate DataType="ContentPresenter">
<Grid>
<StackPanel Name="spImg" Orientation="Horizontal">
<Image Name="img"
Source="{Binding icon}"
Width="20" Height="20" Stretch="Fill" VerticalAlignment="Center" />
<TextBlock Text="{Binding Title}" Margin="5,0" VerticalAlignment="Center" />
<Button x:Name="btnReload"
Visibility="{Binding Reloadbtn}"
Height="14" VerticalAlignment="Center"
Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TreeViewItem}}}"
>
<TextBlock FontSize="9" Text="Reload..." TextAlignment="Center" VerticalAlignment="Center" HorizontalAlignment="Center"></TextBlock>
</Button>
<StackPanel Name="spLoading" Orientation="Horizontal"
Visibility="{Binding spLoading}"
>
<Grid Height="13" MinWidth="50" MaxWidth="75" Margin="5,0" >
<ProgressBar Name="pbLoading"
Height="13"
MinWidth="50"
MaxWidth="75"
IsIndeterminate="True"
HorizontalAlignment="Center"
VerticalAlignment="Center">
</ProgressBar>
<TextBlock Name="txtLoading" Text="Loading..." FontSize="8.6" Margin="5,0" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="Red"/>
</Grid>
<Button Name="btnCancelLoad"
IsEnabled="$True"
Height="14" VerticalAlignment="Center"
Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TreeViewItem}}}"
>
<TextBlock FontSize="9" Text="Cancel" TextAlignment="Center" VerticalAlignment="Center" HorizontalAlignment="Center"></TextBlock>
</Button>
</StackPanel>
</StackPanel>
</Grid>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</TreeView.Resources>
</TreeView>
<Button Name="btnTest" Height="25" VerticalAlignment="Bottom" IsEnabled="$True">Add Item</Button>
</Grid>
</Window>
"#
$reader=(New-Object System.Xml.XmlNodeReader $xaml)
$Window=[Windows.Markup.XamlReader]::Load( $reader )
$treeView=$Window.FindName("foldersTree")
$tstBTN=$Window.FindName("btnTest")
$treeview.add_SelectedItemChanged({
$sender = $args[0]
Write-Host $this.selecteditem.Title
})
$tstBTN.add_Click($btnReload_click)
$myDATA=New-Object System.Collections.ObjectModel.ObservableCollection[object]
$MyItemsListProperty = #(New-Object PSObject -Property #{Title='Image with computer';icon="C:\temp\computer.png";Reloadbtn="Visible";spLoading="Hidden"})
$myDATA.Add($MyItemsListProperty)
$MyItemsListProperty = #(New-Object PSObject -Property #{Title='Image with folder';icon="C:\temp\folder.png";Reloadbtn="Visible";spLoading="Hidden"})
$myDATA.Add($MyItemsListProperty)
$MyItemsListProperty = #(New-Object PSObject -Property #{Title='Image with diskdrive';icon="C:\temp\diskdrive.png";Reloadbtn="Visible";spLoading="Hidden"})
$myDATA.Add($MyItemsListProperty)
#$myWindow_btnReload.Add_Click($btnReload_click)
$treeView.ItemsSource = $myDATA
$Window.ShowDialog()|Out-Null