I can not call a public method of another class from a Click Button on my MainPage

public partial class MainPage : TabbedPage
//the boton
public void MapaPuntaHelena_Clicked(object sender, EventArgs e)
{
Navigation.PushAsync(new MapaPage());
BurroLocation();
}

//the other page xml with code behind
public partial class MapaPage : ContentPage

public void BurroLocation ()

    {
            MyMap.MoveToRegion(
            MapSpan.FromCenterAndRadius(new Position(28.687525, -13.83353), Distance.FromKilometers(5)));  
    }