Grid + Entry : entry does not work...

Hi.
I've this situation:

            var editPrezzo = new Entry();
            editPrezzo.SetBinding(Entry.TextProperty,"ImportoArt");
            editPrezzo.IsVisible = false;

            var labelNome = new Label();
            labelNome.FontSize = Library.GetFontNamedSize(NamedSize.Large, typeof(Label));
            labelNome.SetBinding(Label.TextProperty, "NomeImporto");
            labelNome.XAlign = TextAlignment.Center;
            labelNome.YAlign = TextAlignment.Center;
            labelNome.FontSize = Library.GetFontNamedSize(NamedSize.Medium, typeof(Label));

            var tapGestureRecognizer = new TapGestureRecognizer();
            tapGestureRecognizer.Tapped += (s, e) => {
                if(s.Equals(labelNome)) {
                    editPrezzo.IsVisible = true;
                    editPrezzo.InputTransparent = true;
                    labelNome.IsVisible = false;
                }
                else{
                    editPrezzo.IsVisible = false;
                    editPrezzo.InputTransparent = false;
                    labelNome.IsVisible = true;
                }
            };
            labelNome.GestureRecognizers.Add(tapGestureRecognizer);
            editPrezzo.GestureRecognizers.Add(tapGestureRecognizer);

I have these 2 controls in the same grid cell
grid.Children.Add(labelNome,1,3,0,2);
grid.Children.Add(editPrezzo,1,3,0,2);

I would like that, when I tap on labelNome, editPrezzo appears and vice versa.
infact editPrezzo appears, but I can't write anything. the keyboard does not appear and If I tap on editPrezzo, the Tap does not raise...
It seems that editPrezzo is "disabled"...

Someone can solve this problem?

Thanks
Alessandro