Cannot install Xamarin.Forms.Labs.Core

Hi, I'm trying to install Xamarin.Forms.Labs.Core version 1.2.0 (latest) from NuGet, but getting an Operation Failed:

Could not install package 'Xamarin.Forms 1.2.3.6257'. You are trying to install this package into a project that targets 'portable-net45+win+wpa81+wp80+MonoAndroid10+xamarinios10+MonoTouch10', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.

The Xamarin.Forms PCL solution targets Android, IOS and Windows Phone. Is it perhaps because Labs does not support all three solutions?

I am running:
Windows 8.1
VS2013 Update 4
Xamarin.Forms 1.3.4.6332
Xamarin For Visual Studio 3.9.289
NuGet Package Manager 2.8.50926.663