PushAsync() from PushModalAsync()

Hello all,

i have the following problem im pushing from a NavigationPage PushModelAsync(). My goal is now to push from this Modal a new Navigation Page which refers again back to my current NavigationPage.

it looks like this.

button.Clicked += (object sender, EventArgs e) => { 
    Navigation.PushModalAsync(new MyApp.Views.TaskDetailView(card)); 
};

From this Modal i come back to my root NavigationPage over a cancel button. So now from my TaskDetailView i doing this.

startButton.Clicked += (object sender, EventArgs e) => { 
    Navigation.PushAsync (card.page); 
};

This fails because im pushing a new Page from the Modal Page. Following error is comming "PushAsync is not supported globally on iOS, please usa navigationPage".

I just want to have a popup detail view from which i can go on to a other NavigationPage.

Thanks for your help in advance.