可访问性不一致：参数/属性类型

Question

我已经看到了各种各样的线索，但无法解决我的问题。我有两个错误：

  

可访问性不一致：参数/属性类型＆＃39; TestingApp.KIL＆＃39;比方法/属性更不易访问＆＃39; TestingApp.KILInputPopupWindow.KILInputPopupWindow（TestingApp.KIL）＆＃39; /TestingApp.KILInputPopupWindow.EditedKIL'

namespace TestingApp
{
    public partial class KILInputPopupWindow : Window
    {
        public static readonly DependencyProperty EditedKILProperty = DependencyProperty.Register("EditedKIL", typeof(KIL), typeof(KILInputPopupWindow));
        public KIL EditedKIL
        {
            get { return (KIL)this.GetValue(EditedKILProperty); }
            set { this.SetValue(EditedKILProperty, value); }
        }


        public KILInputPopupWindow(KIL editedKIL)
        {
            InitializeComponent();

            EditedKIL = editedKIL;
        }


        private void Close_Popup(object sender, RoutedEventArgs e)
        {
            DialogResult = true;

            Close();
        }
    }
}

为什么会发生这种情况？