The event '{0}' has a non-standard type. If this event is declared in another CLI language, you may need to access this event ...

The event '{0}' has a non-standard type. If this event is declared in another CLI language, you may need to access this event using the explicit {1} and {2} methods for the event. If this event is declared in F#, make the type of the event an instantiation of either 'IDelegateEvent<_>' or 'IEvent<_,_>'.