Transitionz affects IsEnabled binding

[wjax]

When using "Transitionz" to animate visibility we lose the IsEnabled property

tz:Transitionz.Opacity="{tz:OpacityParams From=0, To=1, Duration=200, TransitionOn=Visibility}"
tz:Transitionz.Translate="{tz:TranslateParams From='10,0', To='0,0', Duration=200, TransitionOn=Visibility}"
tz:Transitionz.Visibility="{Binding ElementName=L_Peers, Path=SelectedItems.Count, Converter={conv:NumElements2Visibility}}"

If we use on the same control:
IsEnabled="{Binding IsRecording, Converter={conv:InvertBoolean}}"

Nothing happens. IsEnabled is not being respected. However if I remove the "tz:" clauses, everything works

Thanks