XamForms Tabs

AppBootstrapper

public Page CreateMainPage()
{
    var tabs = new TabbedPage();
    var vm1 = new SiteListViewModel(); // Implements IScreen
    var tab1 = new RoutedViewHost();
    
    tab1.Router = vm1.Router;
    vm1.Router.Navigate.Execute(vm1);
    
    tabs.Children.Add(tab1);

    return tabs;
}

Exception

12-11 14:19:00.431 I/MonoDroid(29134): System.InvalidOperationException: NavigationPage must have a root Page before being used. Either call PushAsync with a valid Page, or pass a Page to the constructor before usage.
12-11 14:19:00.431 I/MonoDroid(29134): at Xamarin.Forms.Platform.Android.Platform.UpdateActionBar () <IL 0x0008c, 0x003dc>
12-11 14:19:00.431 I/MonoDroid(29134): at Xamarin.Forms.Platform.Android.Platform.SetPage (Xamarin.Forms.Page) <IL 0x000b1, 0x00557>
12-11 14:19:00.431 I/MonoDroid(29134): at Xamarin.Forms.Platform.Android.AndroidActivity.SetPage (Xamarin.Forms.Page) <IL 0x000b6, 0x0045b>
12-11 14:19:00.431 I/MonoDroid(29134): at Cefas.Wavenet.Mobile.Droid.MainActivity.OnCreate (Android.OS.Bundle) [0x00031] in d:\GitHub\Cefas.Wavenet\Cefas.Wavenet.Mobile\Cefas.Wavenet.Mobile.Android\MainActivity.cs:28
12-11 14:19:00.431 I/MonoDroid(29134): at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00011] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.20-series/ba9bbbdd/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:2179
12-11 14:19:00.431 I/MonoDroid(29134): at (wrapper dynamic-method) object.af9f8aa5-233a-4e18-a261-63ea6dca9460 (intptr,intptr,intptr) <IL 0x00017, 0x00043>
12-11 14:19:00.445 W/art     (29134): JNI RegisterNativeMethods: attempt to register 0 native methods for android.runtime.JavaProxyThrowable