MVVM ViewModel에서 클래스의 인스턴스에 ListBox SelectedItem을 넣는 방법

내 ListBox의 SelectedItem에 문제가 있습니다. 내 HealthDiseaseViewModel의 Highlighted 속성에 선택한 항목을 넣고 싶습니다. 여기 내 ViewModel이 있습니다.

public class HealthDiseaseViewModel : ObservableCollection<HealthDisease>
{
    private string _feedBack;

    HealthDiseaseDb _db = new HealthDiseaseDb();

    public HealthDiseaseRetrieveSingleCommand RetrieveSingleCommand { get; set; }
    public HealthDiseaseRetrieveManyCommand RetrieveManyCommand { get; set; }   
    public HealthDiseaseUpdateCommand UpdateCommand { get; set; }   

    public HealthDisease Entity { get; set; }
    public HealthDisease Highlighted { get; set; }
    public List<HealthDisease> EntityList { get; set; }

    public HealthDiseaseViewModel()
    {
        RetrieveSingleCommand = new HealthDiseaseRetrieveSingleCommand(this);
        RetrieveManyCommand = new HealthDiseaseRetrieveManyCommand(this);       
        UpdateCommand = new HealthDiseaseUpdateCommand(this);       
        Highlighted = new HealthDisease();

        Entity = new HealthDisease();
        RetrieveMany(Entity);
    }

    #region Methods

    public void Retrieve(HealthDisease parameters)
    {
        Highlighted = _db.Retrieve(parameters);            
    }

    public void RetrieveMany(HealthDisease parameters)
    {
        EntityList = new List<HealthDisease>();

        EntityList = _db.RetrieveMany(parameters);      

        IList<HealthDisease> toBeRemoved = Items.ToList();

        foreach (var item in toBeRemoved)
        {
            Remove(item);
        }

        foreach (var item in EntityList)
        {
            Add(item);
        }           
    }

    public void Insert(HealthDisease entity)
    {
        bool doesExist = false;
        if (_db.Insert(entity, SessionHelper.CurrentUser.Id, ref doesExist))
        {
            _feedBack = "Item Successfully Saved!";
            RetrieveMany(new HealthDisease());
        }
        else if (doesExist)
        {
            _feedBack = "Item Already Exists!";
        }
        else
        {
            _feedBack = "Not All Fields Were Filled-In!";
        }
        MessageBox.Show(_feedBack, "Item Insertion");
    }

    public void Update(HealthDisease entity)
    {
        bool doesExist = false;

        if (_db.Update(entity, SessionHelper.CurrentUser.Id, ref doesExist))
        {
            _feedBack = "Item Successfully Updated!";
            RetrieveMany(new HealthDisease());
        }
        else if (doesExist)
        {
            _feedBack = "Item Already Exists!";
        }
        else
        {
            _feedBack = "Not All Fields Were Filled-In!";
        }
        MessageBox.Show(_feedBack, "Item Edition");
    }

    public void Delete(HealthDisease entity)
    {
        var answer = MessageBox.Show(String.Format("Are you sure you want to delete \n{0}?", entity.Name), 
        "Item Deletion", MessageBoxButtons.YesNo);

        if (answer == DialogResult.No)
        {
            return;
        }

        if (_db.Delete(entity, SessionHelper.CurrentUser.Id))
        {
            _feedBack = "Item Successfully Deleted!";
            RetrieveMany(new HealthDisease());
        }

        MessageBox.Show(_feedBack, "Item Deletion");
    }   
    #endregion   
}

내 ListBox의 SelectedItem을 Highlighted에 바인딩하고 Highlighted.Name 및 Highlighted.Description을 TextBlocks에 원했지만 TextBlocks에 SelectedItem이 표시되지 않습니다. SelectedItem.Name 및 SelectedItem.Description을 사용하여이 문제를 해결할 수 있지만 문제는 아직 저장 버튼을 누르지 않아도 자동으로 ListBox를 업데이트한다는 것입니다. 강조 표시된 개체를 사용하면이 문제가 해결되지만 지금은 몇 시간 동안 좌절감을 느끼고 있습니다. 여기 내 마크 업이 있습니다. 내 ViewModel에서 UpdateCommand에 바인딩 된 SaveButton을 생략했습니다.

<Grid Name="MainGrid" Background="Aqua" MinWidth="500" MinHeight="400" 
      DataContext="{Binding Source={StaticResource HealthViewModel}}">

    <StackPanel Orientation="Vertical">
        <TextBlock Text="{Binding Path=Highlighted.Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></TextBlock>
        <ListBox x:Name="EntityListBox" Margin="10,0" Height="380"
            ItemsSource="{Binding }"
            DisplayMemberPath="Name"
            SelectedItem="{Binding Path=Highlighted, Mode=TwoWay, 
                                   Converter={StaticResource ToHealthDiseaseConverter}, 
                                   UpdateSourceTrigger=PropertyChanged}" />
    </StackPanel>   
</Grid>