XAML Maps

Hello,

Using C# I am able to create a maps control on a view. However, when trying to do this using XAML I get the following error:

/MyProject.Forms/packages/Xamarin.Forms.1.0.6188/build/portable-win+net45+wp80+MonoAndroid10+MonoTouch10/Xamarin.Forms.targets: Error: Error executing task XamlG: Can't load types from xmlns clr-namespace:Xamarin.Forms.Maps;assembly=Xamarin.Forms.Maps (MyProject.Forms)

This is my XAML:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
                       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                       xmlns:maps="clr-namespace:Xamarin.Forms.Maps;assembly=Xamarin.Forms.Maps"
                       x:Class="MyProject.Forms.MainPage">
    <maps:Map x:Name="MyMap" />
</ContentPage>

Any ideas?

Stephen