Android Tabbed Page don't work

I have following Problem. I created a Tabbed Page which works finde on iOS but on Android it don't show the tabs on the upper bar as usual. I Create it like this

var page1 = new Page1();
var page2 = new Page2();
var page3 = new Page3();

var tabbedPage = new TabbedPage {
Title = "Test",
Children = {
page1,
page2,
page3
},
CurrentPage = page1,
};

And then create a new NavigationPage as my Detail Page.

Master = menuPage;
Detail = new NavigationPage (tabbedPage) {
BarBackgroundColor = Styles.AppColor,
BarTextColor = Color.White
};

I don't now why it doesn't work :-/