PRISM 4 RadPane Static region

[Ubuntu]

Dear All,

I want to use the RadPanes as a static regions and to be able to use the PRISM4 navigation within this pane region.
Is there any simple way to implement such scenario.

I already have this declaration:

<telerik:RadDocking x:Name="designdock" Grid.Row="1" Background="Silver" BorderBrush="Silver">
    <telerik:RadDocking.DocumentHost>
        <telerik:RadSplitContainer x:Name="desginspliter" Orientation="Vertical">
            <telerik:RadPaneGroup x:Name="unpostedRegion">
                <telerik:RadPane
                    prism:RegionManager.RegionName="DailyUnPostedRegion"
                    prism:RegionManager.RegionManager="{Binding Path=RegionManager}">
                </telerik:RadPane>
            </telerik:RadPaneGroup>
            <telerik:RadPaneGroup x:Name="postedRegion">
                <telerik:RadPane
                    prism:RegionManager.RegionName="DailyPostedRegion"
                    prism:RegionManager.RegionManager="{Binding Path=RegionManager}">
                </telerik:RadPane>
            </telerik:RadPaneGroup>
        </telerik:RadSplitContainer>
    </telerik:RadDocking.DocumentHost>
</telerik:RadDocking>

But when I need to navigate within the same region a receive an error saying "system.controls is already assigned to an object something like that" ...

any help !!