在prism的EventAggregator事件订阅会指向一个方法，而该方法不能为private，否则该事件订阅将会无法方法该方法导致订阅错误！正确做法是将指向的方法改为public

[ImportingConstructor]
        public ApplicationViewModel(IEventAggregator eventAggregator, IRegionManager regionManager)
        {
            this.EventAggregator = eventAggregator;
            this.RegionManager = regionManager;
            this.EventAggregator.GetEvent<ModuleChangedEvent>().Subscribe(OnLoading, ThreadOption.UIThread);
        }

public void OnLoading(SYS_MODULE curModule)
        {
            this.IsBusy = true;
            EntityQuery<SYS_APPLICATIONS> list = this.AuthenticationContext.GetSYS_APPLICATIONSQuery().Where(p => p.A_MODULEID == curModule.MODULEID);
            LoadOperation<SYS_APPLICATIONS> loadop = this.AuthenticationContext.Load(list);
            loadop.Completed += new EventHandler(loadop_Completed);
 
        }