使用mvvm在Uwp中的System.TypeInitializationException？

Question

的ResourceDictionary：

<Page DataContext="{Binding Source={StaticResource Construction}, Path=AddEngineerViewModel}"/>

addEngineerView.xaml

public class ConstructionLocator
{

    private static IDialogServices _dialog = new DialogServices();
    private static IAddEngineerDataService _addEngineerDataServices = new AddEngineerDataServices(new AddEngineerData());

    private static AddEngineerViewModel _addEngineerViewModel = new AddEngineerViewModel(_addEngineerDataServices, _dialog);
    private static ViewEmployeeViewModel _viewEmployeeViewModel = new ViewEmployeeViewModel(_addEngineerDataServices, _dialog);


    public static AddEngineerViewModel AddEngineerViewModel
    {
        get { return _addEngineerViewModel; }
    }

    public static ViewEmployeeViewModel ViewEmployeeViewModel
    {
        get { return _viewEmployeeViewModel; }
    }

}

定位器：

public class AddEngineerViewModel:BindableBase
{
    IAddEngineerDataService _engineerDataService;
    IDialogServices _dialog;

    public AddEngineerViewModel(IAddEngineerDataService AddEngineerDataService,IDialogServices Dialog)
    {
        _engineerDataService = AddEngineerDataService;
        _dialog = Dialog;
        LoadCommand();
    }

    private AddEngineerModel _addEngineer;
    public AddEngineerModel AddEngineer
    {
        get { return _addEngineer; }
        set
        {
            _addEngineer = value;
            RaisePropertyChanged("AddEngineer");
        }
    }

    public ICommand AddEngineerCommand { get; set; }
    public ICommand ViewEngineerCommand { get; set; }

    private void LoadCommand()
    {
        AddEngineerCommand = new CustomCommand(Add, CanAdd);
        ViewEngineerCommand = new CustomCommand(Views, CanView);
    }

    private void Views(object obj)
    {
        _dialog.ShowDialog();
    }

    private bool CanView(object obj)
    {
        return true;
    }

    private bool CanAdd(object obj)
    {
        return true;
    }

    private void Add(object obj)
    {
        _engineerDataService.Add_Engineer_Details(_addEngineer);
    }
}

视图模型：

{{1}}

当导航到按钮上的视图时，单击它会显示类型初始值设定项在addengineerviewmodel静态属性的定位器文件中引发异常。以上是我的定位器和视图模型。会有什么问题？