Exception while registering Region in RegionManager

Hi All

We are using ActiPro 11.2 license Software but we are facing problem when we are implementing docking in Prism4 using Prism MEF

But it is throwing exception while registering Region in RegionManager

Here is sample:

[ImportingConstructor]

public RealTimeModule(IRegionManager regionManager, IRegionViewRegistry registry, IEventAggregator evntAggregator)
{

this.regionManager = regionManager;

this.myRegionViewRegistry = registry;

this.eventAggregator = evntAggregator;

}

public void Initialize()
{

try
{

realTimeShell = new RealTimeShell();

RegionManager.SetRegionManager(realTimeShell, regionManager);

AblationViewModel ablationViewModel = new AblationViewModel();      //This is our view model

this.regionManager.Regions["MainRegion"].Add(ablationViewModel);    //Adding view model to RegionManagers' Region

}

Here is Assembly Reference in my application

ActiproSoftware.Docking.Interop.Prism.Wpf     //Compiled assembly from downloaded code from http://actipro.codeplex.com/

ActiproSoftware.Docking.Wpf

ActiproSoftware.Shared.Wpf

Microsoft.Practices.Prism

Microsoft.Practices.Prism.MefExtensions

System.ComponentModel.Composition

…

This assembly[ActiproSoftware.Docking.Interop.Prism.Wpf] we get it after compiling code from http://actipro.codeplex.com/

So please provide solution to us