I need some quick help which is a road blocker for me now. I have Button in ItemsControl and I need to perform some task on Button click. I tried adding Command to Button in ItemsControl DataTemplate but its not working. Can anyone suggest how to proceed further.

<UserControl.Resources>
    <DataTemplate x:key="mytask">
        <TextBox Grid.Row="5" Grid.Column="2" Text="{Binding Path=PriorNote}" Grid.ColumnSpan="7"  VerticalAlignment="Center" HorizontalAlignment="Left" Margin="0,5" Width="505" Foreground="Black"/>
        <StatusBarItem Grid.Row="2" Grid.Column="8" Margin="8,7,7,8" Grid.RowSpan="2">
        <Button x:Name="DetailsButton" Command="{Binding CommandDetailsButtonClick}">
    </DataTemplate>
</UserControl.Resources>

<Grid>
    <ItemsControl Grid.Row="1" 
                  ItemsSource="{Binding ListStpRules}" 
                  ItemTemplate="{StaticResource myTaskTemplate}" Background="Black"
                  AlternationCount="2" >
    </ItemsControl>
</Grid>

and in ViewModel I have implemented code for Command. And its not working. Please suggest any solution for me to proceed further

The DataContext of each item in your ItemsControl is the item in the collection the ItemsControl is bound to. If this item contains the Command, your code should work fine.

However, this is not usually the case. Typically there is a ViewModel containing an ObservableCollection of items for the ItemsControl, and the Command to execute. If this is your case, you'll need to change the Source of your binding so it looks for the command in ItemsControl.DataContext, not ItemsControl.Item[X]

<Button Command="{Binding 
    RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}, 
    Path=DataContext.MyCommand}" />