Why is my DataStateBehavior not working

Question

DataStateBehavior isn't working. Is there a trick to make it work when properties are nested?

<i:Interaction.Behaviors>
            <ic:DataStateBehavior x:Name="DataStateBehaviorCustomIndexButton"  Binding="{Binding ViewModel.ButtonVisibleFlag, Mode=TwoWay}" TrueState="ButtonVisible" FalseState="ButtonHidden"/>
        </i:Interaction.Behaviors>

Answer 1

As it turns out I didn't understand what value does.

I thought it was initial value, but instead it was the value that triggers a true/false.