如何使用C#中的对象ID属性获取对象值

这是我在windowsphone 8应用程序开发方面的第一次经验。我有一个问题，我在下面提到，你能帮我解决吗？

我通过Activities.xaml中的数据绑定显示ActivityViewModel中的数据当用户点击活动项目时，我会将ActivityID发送到ActivityDetails.xaml。我正在尝试使用ActivityID调用创建为AccountAction的对象。

如何使用ActivityDetails.xaml.cs中的ActivityID获取对象值(ActivityImage、ActivityName、ActivityAmon…(？

ActivityViewModel:

public class ActivityViewModel
{
    public ObservableCollection<AccountAction> ActivityItemCollection { get; set; }
    public ActivityViewModel()
    {
        ActivityItemCollection = new ObservableCollection<AccountAction>();

        ActivityItemCollection.Add(new AccountAction()
        {
            ActivityID = "SP0001",
            ActivityImage = "/Images/Logos/e-bay.png"
            ActivityName = "E-Bay",
            ActivityAmount = "100,00",
            ActivityDate = "Today",
            ActivityHour = "11:49"
        });
       .
       .
       .
    }
}

Activities.xaml.cs

 private void StackPanel_Tap(object sender, System.Windows.Input.GestureEventArgs e)
    {
        var _ActivityID = Convert.ToString(((StackPanel)sender).Tag);
        NavigationService.Navigate(new Uri("/ActivityDetails.xaml?ActivityID=" + _ActivityID, UriKind.Relative));
    }

ActivityDetails.xaml.cs

 protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        base.OnNavigatedTo(e);
        string ActivityID = "";
        if (NavigationContext.QueryString.TryGetValue("ActivityID", out ActivityID))
        {
            ReferanceNumber.Text = ActivityID;
        }
    }

 protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        string ActivityID;
        if (e.IsNavigationInitiator  && this.NavigationContext.QueryString.TryGetValue("ActivityID", out ActivityID))
        {
          ActivityID= int.Parse(ActivityID);
        }
    }

AccountAction result = ActivityItemCollection.FirstOrDefault(act=>act.ActivityID == ActivityID);