WPF双向数据绑定列表框无法获得选定值

我正在努力与WPF中的数据绑定进行搜索，我仍然看不到我缺少什么来获得模型以从列表中选择项目更新。我有两个实体一个Slot和一个SlotType

public class Slot : BindableObject, INotifyPropertyChanged
{
    private int slotID;
    public int SlotID
    {
        get { return slotID; }
        set
        {
            if (slotID != value)
            {
                slotID = value;
                RaisePropertyChanged("SlotID");
            }
        }
    }
    private string user;
    public string SlotUser
    {
        get { return user; }
        set
        {
            if (user != value)
            {
                user = value;
                RaisePropertyChanged("SlotUser");
            }
        }
    }
    private int slotUserID;
    public int SlotUserID
    {
        get { return slotUserID; }
        set
        {
            if (slotUserID != value)
            {
                slotUserID = value;
                RaisePropertyChanged("SlotUserID");
            }
        }
    }
    private int slotType;
    public int SlotType
    {
        get { return slotType; }
        set
        {
            if (slotType != value)
            {
                slotType = value;
                RaisePropertyChanged("SlotType");
            }
        }
    }
    private DateTime slotStartDateTime;
    public DateTime SlotStartDateTime
    {
        get { return slotStartDateTime; }
        set
        {
            if (slotStartDateTime != value)
            {
                slotStartDateTime = value;
                RaisePropertyChanged("SlotStartDateTime");
            }
        }
    }
public class SlotType : BindableObject, INotifyPropertyChanged
{
    private int slotTypeID;
    public int SlotTypeID
    {
        get { return slotTypeID; }
        set
        {
            if (slotTypeID != value)
            {
                slotTypeID = value;
                RaisePropertyChanged("SlotTypeID");
            }
        }
    }
    private string slotTypeDesc;
    public string SlotTypeDesc
    {
        get { return slotTypeDesc; }
        set
        {
            if (slotTypeDesc != value)
            {
                slotTypeDesc = value;
                RaisePropertyChanged("SlotTypeDesc");
            }
        }
    }
    public override string ToString()
    {
        return SlotTypeDesc;
    }
}

然后创建一个包含这两个类的类，并将我的窗口上下文设置为这个类。

public class SlotWithTypes 
{
    public ObservableCollection<SlotType> slotTypes { get; set; }
    public Slot slot { get; set; }
}

从我的主窗口，我测试，如果需要打开一个新的窗口，显示槽类型的列表，供用户选择哪个类型是相关的插槽创建。

Slot slot = new Slot();
slot.SlotStartDateTime = item.SlotStartDateTime;
if (item.SlotType == 0)
{
    SlotWithTypes swtype = new SlotWithTypes();
    swtype.slotTypes = slotTypes;
    swtype.slot = slot;
    SelectSlotType stype = new SelectSlotType();
    stype.DataContext = swtype;
    stype.ShowDialog();
}

最后在XAML中我有一个列表框

<Grid>
    <ListBox Name="lstSlotTypes" 
             HorizontalAlignment="Left" 
             Height="200" 
             Margin="0,10,0,0" 
             VerticalAlignment="Top" 
             Width="194"                 
             ItemsSource="{Binding slotTypes}" 
             SelectedItem="{Binding Path=slot.Type, Mode=TwoWay}"
             SelectedValue="{Binding slotTypes.SlotTypeID, Mode=TwoWay}" 
             SelectedValuePath="{Binding slot.Type, Mode=TwoWay}" 
             DisplayMemberPath="{Binding slotTypes.SlotTypeDesc}"                  
             SelectionChanged="lstSlotTypes_SelectionChanged">
    </ListBox>
    <TextBox HorizontalAlignment="Left" 
             Height="23" 
             Margin="10,246,0,0" 
             TextWrapping="Wrap" 
             Text="{Binding slot.SlotStartDateTime, Mode=TwoWay}" 
             VerticalAlignment="Top" 
             Width="74"/>
</Grid>

为了测试，我放入一个绑定到slotstartdatetime的文本框，它可以工作并更新回我的模型。我已经在列表框上尝试了各种绑定格式，并且可以获得我的SlotTypes列表来显示put，无法获得Slot实体以所选值更新。

我意识到这已经成为一个很长的问题，但请如果有人能看到我做错了什么?