Null value in expression

[CreateLab]

try to bind like in your sample

<ListBox x:Name="listBox" Grid.Row="3" Grid.Column="1" Items="{Binding Collection}"
                 SelectedItem="{Binding ShowObject}" >
            <i:Interaction.Behaviors>
                <ia:EventTriggerBehavior EventName="DoubleTapped" SourceObject="{Binding #listBox}">
                    <ia:InvokeCommandAction Command="{Binding EnterClickCommand}" />
                </ia:EventTriggerBehavior>
            </i:Interaction.Behaviors>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <Image Source="{Binding Bitmap}" MaxHeight="25" MaxWidth="25" />
                        <TextBlock Text="{Binding Name}" />
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

but have an exception in debug output
[Binding] Error in binding to "Avalonia.Xaml.Interactions.Core.InvokeCommandAction"."Command": "Null value in expression ''." (Avalonia.Xaml.Interactions.Core.InvokeCommandAction #63183526)

use Avalonia 0.8.999
use behaviors 0.9.0

[wieslawsoltes]

@CreateLab Where is the EnterClickCommand defined?

[CreateLab]

@wieslawsoltes open agein and if u can contact with me in gitter
in vm

 public ReactiveCommand<Unit,Unit> DownloadFileCommand { get; }
        public ReactiveCommand<Unit,Unit> EnterClickCommand { get; }
   EnterClickCommand = ReactiveCommand.Create(() => Console.Write("fsdfsd"));