System.NullReferenceException Xamarin Maps - xamarin

Question

I'm getting a NullException when will display the map, but can not detect;
I tried to change the name of the maps, locazation, etc., but without success.
You may be able to identify where is my mistake, please help me!
public partial class LocationPage : ContentPage
{
public Clinica _clinica;
public LocationPage(Clinica clinica)
{
InitializeComponent();
Clinica = clinica;
SetupMap();
}
public Clinica Clinica
{
get
{
return _clinica;
}
set
{
_clinica = value;
}
}
protected override void OnAppearing()
{
base.OnAppearing();
// Typically, is preferable to call into the viewmodel for OnAppearing() logic to be performed,
// but we're not doing that in this case because we need to interact with the Xamarin.Forms.Map property on this Page.
// In the future, the Map type and it's properties may get more binding support, so that the map setup can be omitted from code-behind.
SetupMap();
}
void SetupMap()
{
if (Device.OS != TargetPlatform.WinPhone && Device.OS != TargetPlatform.Windows)
{
var pin = new Pin()
{
Type = PinType.Place,
Position = new Position(Clinica.Latitude, Clinica.Longitude),
Label = Clinica.Nome
};
clinicaMap.Pins.Clear();
clinicaMap.Pins.Add(pin);
clinicaMap.MoveToRegion(MapSpan.FromCenterAndRadius(pin.Position, Distance.FromMiles(10)));
}
}
}
}
LocationPage.xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:maps="clr-namespace:Xamarin.Forms.Maps;assembly=Xamarin.Forms.Maps"
x:Class="CartaoDeTodos.View.LocationPage">
<StackLayout>
<maps:Map x:Name="clinicaMap"
VerticalOptions="FillAndExpand"/>
</StackLayout>
</ContentPage>