Open modal view (native) in tabbed page

[bitworked]

I have a tabbed page wrapped in a navigationbar and I want to open a native modal window. With version 8 I can't do it. This is my code:

` <TabbedPage.Children>

<x:Arguments>
<uc:MainPageView />
</x:Arguments>
<NavigationPage.IconImageSource>

</NavigationPage.IconImageSource>

<x:Arguments>
<uc:FavoritesView />
</x:Arguments>
<NavigationPage.IconImageSource>

</NavigationPage.IconImageSource>

</NavigationPage>

</TabbedPage.Children>`
Open the tabbed page like
await _navigationservice.NavigateAsync("/MainTabView?selectedTab=MainPageView");

and I open the window as usual but not work
await _navigationservice.NavigateAsync("NavigationBar/AppInfoView", null, useModalNavigation: true, true);

Can you help me?
Thanks