I am trying to use proguard with Xamarin. So I included it in the project settings (checked Enable ProGuard) and I created the file proguard.cfgin the properties (like a new text file, right?) And checked the BuildAction -> ProguardConfiguration

The proguard file contains only a -keep configuration with a comment. I leave or delete a comment, I always get a parsing error on line 1:
-keep class !android.support.v7.view.menu.**, !android.support.design.internal.NavigationMenu, !android.support.design.internal.NavigationMenuPresenter, !android.support.design.internal.NavigationSubMenu, android.support.** {*;}
I get an error Unknown option '' in line 1.
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/Android/Xamarin.Android.Common.targets: : : 1. : proguard.ParseException: '' 1 '/proguard.cfg'
№ 10 proguard.ConfigurationParser.parse(ConfigurationParser.java:191) proguard.ProGuard.main(ProGuard.java:484) (WheezMe.Droid)
?