DeploymentCatalog IndexOutOfRangeException problem

Question

Hi,

I've a problem that I can't solve.
The part in Bold gives always an "IndexOutOfRangeException".
Can somebody help???    

 public class MainViewModel : ViewModelBase
    {

        [Import(typeof(IJBAEnvironmentViewModel))]
        public IJBAEnvironmentViewModel JBAEnvir { get; set; }

       [ImportMany(AllowRecomposition = true)]
       public Contracts.IScreen[] Screens { get; set; }

        private string _JBAEnvironment;
        private UserControl _Screen;

        public string JBAEnvironment
        {
            get
            {
                return _JBAEnvironment;
            }
            set
            {
                _JBAEnvironment = value;
                RaisePropertyChanged("JBAEnvironment");
            }
        }

        public UserControl Screen
        {
            get
            {
                return _Screen;
            }
            set
            {
                _Screen = value;
                RaisePropertyChanged("Screen");
            }
        }

 

      

        public MainViewModel()
        {          
            App.aggr.Catalogs.Add(CreateCatalog("JBAEnvir.xap"));
        }

        private DeploymentCatalog CreateCatalog(string uri)
        {
            DeploymentCatalog catalog = new DeploymentCatalog(new Uri(uri, UriKind.Relative));
            CompositionHost.Initialize(catalog);
            catalog.DownloadCompleted += (s, e) =>
            {
                if (e.Error != null)
                {
                    string ssss = e.Error.Message;
                }
                else
                {
                    CompositionInitializer.SatisfyImports(this);
                    JBAEnvironment = JBAEnvir.GetJBAEnvironment();
                    //JBAEnvir.Test(JBAEnvironment);
                    //IsUnderMaintenance = JBAEnvir.IsUnderMaintenance;                   
                   
                    string thedate = DateTime.Now.ToString("yyyy-MM-d-HH.mm.ss.000000");
                    MaintenanceSvc.maintenanceServicePortTypeClient ctx = new MaintenanceSvc.maintenanceServicePortTypeClient(new BasicHttpBinding(), new EndpointAddress("http://myLink/maintenance.php"));
                    ctx.setMaintenanceCompleted += (ss, ee) =>
                    {

                        if (ee.Result.Equals("none"))
                        {
                            App.aggr.Catalogs.Add(CreateCatalog2("Start.xap"));                                                              
                        }
                        else
                        {
                            App.aggr.Catalogs.Add(CreateCatalog2("Maintenance.xap"));                                                      
                        }
                    };
                    ctx.setMaintenanceAsync(thedate);                    
                }
              
            };
            catalog.DownloadAsync();
            return catalog;
        }

        private DeploymentCatalog CreateCatalog2(string xap)
        {
          
            DeploymentCatalog catalog = new DeploymentCatalog(new Uri(xap, UriKind.Relative));
          
            catalog.DownloadCompleted += (s, e) =>
            {
                if (e.Error != null)
                {
                    string ss = e.Error.Message;
                }
                else
                {
                    CompositionInitializer.SatisfyImports(this);                    
                   Screen = Screens[0].getUserControl();                                        
                }
            };
            catalog.DownloadAsync();
            return catalog;  
        }
    }