Forms.Labs ExtendedLabel - Text without underline

Hello, i've a my project in a xamarin.Forms. When i import the only files related to the control ExtendedLabel(from Forms.Labs) , and put the realtive costructor of ExtendedLabel the text appear without underline

I create the costructor and put it in StackLayout but the relative label don't appear with underline

How this is possible ?

this is my code

var lblMyLabel = new ExtendedLabel {
Text = "I am a label",
IsUnderline = true,
BackgroundColor = Color.Aqua,
HorizontalOptions = LayoutOptions.Center
};

Content = new StackLayout
{
Spacing = 10,
Children = { lblMyLabel }
};

Thanks

Alex