"MMC has detected an error in a snap-in and will unload it" when adding a particular Role or roles services

 I have the following error when adding roles services for RDS Gateway. Server Manager snap-in is working fine  when adding other roles services except the RDS Gateway. am running Windows 2008 R2 Sp1

at Microsoft.ManagementConsole.Internal.SnapInMessagePumpProxy.OnThreadException(Object sender, ThreadExceptionEventArgs e)
   at System.Windows.Forms.Application.ThreadContext.OnThreadException(Exception t)
   at System.Windows.Forms.Control.WndProcException(Exception e)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
   at Microsoft.ManagementConsole.Internal.ConsoleDialogHost.ShowDialog(WaitCursor waitCursor, ShowDialogCallback callback)
   at Microsoft.ManagementConsole.Advanced.Console.ShowDialog(Form form)
   at Microsoft.Windows.ServerManager.ServerManagerSnapIn.ShowModalDialog(Form dialog)
   at Microsoft.Windows.ServerManager.ServerManagerSnapIn.ShowFeaturesWizard(Boolean addingFeatures, Boolean optionalComponents, InstallableRoleInformation primaryRole, SqmInstallEntryPoint sqmEntryPoint)
   at Microsoft.Windows.ServerManager.RoleNode.OnAction(Action action, AsyncStatus status)
   at Microsoft.ManagementConsole.ScopeNode.DoAction(Int32 actionId, IRequestStatus requestStatus)
   at Microsoft.ManagementConsole.SnapIn.ProcessRequest(Request request)
   at Microsoft.ManagementConsole.Internal.SnapInClient.Microsoft.ManagementConsole.Internal.IMessageClient.ProcessRequest(Request request)
   at Microsoft.ManagementConsole.Internal.IMessageClient.ProcessRequest(Request request)
   at Microsoft.ManagementConsole.Executive.RequestStatus.BeginRequest(IMessageClient messageClient, RequestInfo requestInfo)
   at Microsoft.ManagementConsole.Executive.SnapInRequestOperation.ProcessRequest()
   at Microsoft.ManagementConsole.Executive.Operation.OnThreadTransfer(SimpleOperationCallback callback)