WrapLayout.cs Type 'TDeclarer' does not contain a definition for 'Orientation' error?

In WrapLayout.cs(download link: http://bit.ly/xf-custompanel) provided by @CraigDunn‌ :

/// <summary>
/// Orientation (Horizontal or Vertical)
/// </summary>
public StackOrientation Orientation {
    get { return (StackOrientation)GetValue (OrientationProperty); }
    set { SetValue (OrientationProperty, value); } 
}

/// <summary>
/// Backing Storage for the Orientation property
/// </summary>
public static readonly BindableProperty OrientationProperty = 
    BindableProperty.Create<WrapLayout, StackOrientation> (w => w.Orientation, StackOrientation.Vertical, 
        bindingPropertyChanged: (bindable, oldvalue, newvalue) => ((WrapLayout)bindable).OnSizeChanged ());

Error says Type 'TDeclarer' does not contain a definition for 'Orientation', but it does have, which is just above OrientationProperty's definition(first line).
Anyone could help me out? Thank you. Btw, error appears after I upgraded the xamarin.forms package.