How to use XFGloss on WinPhone 8.1 Xamarin Portable Project

Question

I am making one portable xamarin application and I am using XFGloss . Everything works fine on Android and iOS, but on WinPhone 8.1 my BackGroud Gradiant is still black.

My page has:

<xfg:ContentPageGloss.BackgroundGradient>
  <xfg:Gradient Rotation="150">
      <xfg:GradientStep StepColor="#305E70" StepPercentage="0" />
      <xfg:GradientStep StepColor="#305E70" StepPercentage="1" />
  </xfg:Gradient>
</xfg:ContentPageGloss.BackgroundGradient>

On, Android and iOS, I have to initialize xfgloss, for example:

-Android

XFGloss.Droid.Library.Init(this, bundle);

-iOS

XFGloss.iOS.Library.Init();

And I did not find how to run XFGloss on WinPhone, I even know if it needs to be initialized.

How to do it on WinPhone?