As I've installed VS2017, I took the time to do refactoring on my project in order to add new api.
So I've decide to start from a blank project and add my classes.
After several quirks, I've spent a lot of time to add a splash screen.
When I followed old fashion method or the method Xamarin describes on their website I always had this error:
The main difference is : No layer list to create, and in the style.xml file,
there are those two more item
Now everything works fine.