BackgroundImage when using MasterDetailPage

Hello Guys!

I have a ContentPage, such like this:

ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="XXXXXX"
Title="Title"
BackgroundImage="bg_app.png"
Padding="5"

When I use that page directly in App.Current.MainPage the BackgroundImage appears... But, when I use the same page in MasterDetailPage.Detail, the background image don't works...

When I set MasterDetailPage.BackgroundImage property... The BackgroundImage don't work too.

Any sugestions?