Prism:EventAggregator and MEF - 2 different instances of EventAggregator

У меня следующая настройка:

• Приложение Silverlight разделено на xaps / modules

• Я использую MEF как структуру DI для подключения различные части моего приложения.

• У меня есть 2 региона:

• Одна (левая) заполнена список (например, клиенты)

• Один (правый) заполнен представление, содержащее tabcontrol с район, который я заселил (по к какому клиенту выбран) с другое представление, содержащее элемент управления вкладкой с областью.

  Результат справа:

To populate the first level tabcontrol I am listening to the "customer changed event" - (this works great) and when I get receive the event I populate the First Level tab area with Views:

    Dim lReg As IRegion = Me.mRegionManager.Regions("FirstLevelTabReqion")
    Dim lViewID As String = CommonDefinitions.Constants.BuildFirstLevelViewName(lUniqueID)
    Dim lFirstLevelView FirstLevelView = TryCast(lReg.GetView(lRqViewID), FirstLevelView)
    If lFirstLevelView Is Nothing Then     
         lFirstLevelView = New FirstLevelView()
         Dim lRegMan1 As IRegionManager = lReg.Add(lFirstLevelView, lViewID, True)
         lFirstLevelView.SetRegionManager(lRegMan1)
         ...
    End If

Note: When creating the FirstLevelView I have to throw in a CompositionInitializer.SatisfyImports call to make sure the FirstLevelView resolves its ViewModel reference.

To get an instance of the EventsAggregator in the SecondLevel ViewModel I use:

  <ImportingConstructor()>
  Public Sub New(ByVal iEvAggregator As IEventAggregator)
          EventAggregator = iEvAggregator
          EventAggregator.GetEvent(Of DoStuffSecondLevel).Subscribe(AddressOf OnDoStuffSecondLevel, True)

   End Sub

My problem is that the EventAggregator instance I get in the second level view model is different from the EventAggregator instance in the first level so if I publish DoStuffSecondLevel on the first level it will not be caught in the second level.

Why do I get 2 different instances of the EventAggregator?
What can I do to share the same instance of the EventAggregator across the application?

Thanks in advance