解决Prism的EventAggregator的事件订阅错误

[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);

}