ActivateItem not working in Caliburn.Micro - wpf

Question

I am using Caliburn Micro for MVVM. In my MainView (shell), I have two controls. One hosts a RibbonView and another ContentControl which loads contents depending on the RibbonView menu selection. Here is the MainView (shell)
MainView (shell)
<Window x:Class="HotelReservation.Main.Views.MainView">
<DockPanel>
<ContentControl x:Name="RibbonView" DockPanel.Dock="Top"/>
<Grid DockPanel.Dock="Bottom" VerticalAlignment="Stretch" >
<ContentControl x:Name="ActiveItem"/>
</Grid>
</DockPanel>
</Window>
RibbonView
<Ribbon Margin="0,-20,0,0">
<RibbonTab Header="Room Band">
<RibbonGroup>
<RibbonButton Label="List" x:Name="RoomBandMain"
LargeImageSource="/HotelReservation.Global;component/Images/room-band-list-icon.png">
</RibbonButton>
</RibbonGroup>
</RibbonTab>
</Ribbon>
RibbonViewModel
public class RibbonViewModel : Conductor<object> {
public void RoomBandMain() { //Load in ActiveItem of MainView
ActivateItem(container.GetExportedValue<RoomBandMainViewModel>());
}
}
As can be seen, I am trying to load RoomBandMainViewModel in the <ContentControl x:Name="ActiveItem"/> The issue is that it is not loaded and I get a blank screen even though ActivateItem(container.GetExportedValue<RoomBandMainViewModel>()) code runs. I think that the <ContentControl x:Name="ActiveItem"/> exists not in RibbonView but its parent MainView, and hence the ActivateItem doesn't work.
How to resolve this issue.
Edit:
I had to set the DataContext of the <ContentControl x:Name="ActiveItem"/> to RibbonViewModel, so that ActiveItem is now property of RibbonViewModel and not MainViewModel. MainViewModel looks like below
So the MainView (shell) is now as follows
<Window x:Class="Conductor_Main.Views.MainView">
<DockPanel>
<ContentControl x:Name="RibbonView" DockPanel.Dock="Top"/>
<Grid DockPanel.Dock="Bottom" VerticalAlignment="Stretch" Background="Green"
DataContext="{Binding RibbonView}">
<ContentControl x:Name="ActiveItem" />
</Grid>
</DockPanel>
</Window>
Now the <ContentControl x:Name="ActiveItem" /> actually belongs to the RibbonViewModel.

Answer 1

What you have here is some kind of lifecycle of your windows. This has to be handled by the parent window of your ActiveItem.
The way to get this done the caliburn.micro way is to have a Conductor above the ActiveItem. In your case this is the MainWindow.
Your RibbonViewModel can be a Conductor, too. But only for it's own children. There can be more than one conductor.
From the caliburn documentation
Once you introduce the notion of a Screen Activation Lifecycle into
your application, you need some way to enforce it. This is the role of
the ScreenConductor. When you show a screen, the conductor makes sure
it is properly activated.
Which is quite a direct way of saying: If you have activation / life cycle, then use a conductor.