List View not listens to XAML but Sized as number of initial itemssource.

I have listview. It's Vertical and Horizontal Options are fill in Xaml.
I am setting it's source as somelist in OnAppearing Window.
protected override void OnAppearing() { base.OnAppearing(); ((ListView)FindByName("attributesList")).ItemsSource = d.attributes; }
Listview will size itself as number of items in attributes. If two list view will be size of two rows. If something added it scrolls but size is of only two rows. If initially there is no item. Nothing is shown. If I comment this Itemssource line, The list will expand on whole page as needed.