Use the autoscoll of a listbox while respecting the mvvm - vb.net

Question

I found the sample code of "Nick Miller" on the following question:
mvvm how to make a list view auto scroll to a new Item in a list view
This partly answers my question because scrolling works very close, but I need the user can stop automatic scrolling.
To do this I added a checkbox, and in the eveinement puts it true or false the variable listbox.autoscroll, but this has no effect despite the fact that the code will change the property.
I have not changed the Nick Miller code on the LoggingListBox class.
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Test_Listbox_Autoscroll"
xmlns:tools="clr-namespace:Test_Listbox_Autoscroll"
mc:Ignorable="d"
Title="MainWindow" Width="800"
SizeToContent =" WidthAndHeight">
<Grid>
<StackPanel >
<tools:LoggingListBox x:Name="Listbox1"
Margin=" 10"
Background="Bisque"
Height="180"
ItemsSource="{Binding LST_ListBox1_Collection}"
SelectedItem="{Binding LST_ListBox1_SelectedItem}"/>
<CheckBox x:Name="ChkAutoScroll"
Margin="10"
Content="Auto Scroll"
Click="ChkAutoScroll_Click"/>
</StackPanel>
</Grid>
</Window>
Private Sub ChkAutoScroll_Click(sender As Object, e As RoutedEventArgs)
If (ChkAutoScroll.IsChecked = True) Then
Listbox1.AutoScroll = True
Else
Listbox1.AutoScroll = False
End If
End Sub
There is no error message, but scrolling is still active despite the AutoScroll value change.