Navigation.PushAsync() causing exception

I have a main page, which is a MasterDetailPage, and when a button is clicked, it calls this code:

var newDevice = new AddDeviceView();
                    await Navigation.PushAsync(newDevice);

AddDeviceView is a ContentView with a single Label on:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="LTBLApplication.Views.AddDeviceView"
             Title="homeView"
             BackgroundColor="White"
             >
  <Label Text="{Binding MainText}" VerticalOptions="Center" HorizontalOptions="Center" />
</ContentPage>

When the navigation happens, it throws an "Unhandled Exception". Doesn't show what type, and the call stack can't be viewed. Any ideas?