Set textblock text in a flipview in Metro App C#

Hi,

How can I set the text of a textblock which resides in a flipview, with value that I retrieved from the WCF service?

Here are some codes in the code-behind of ItemDetailPage:

protected async override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
{
    // Allow saved page state to override the initial item to display
    if (pageState != null && pageState.ContainsKey("SelectedItem"))
    {
        navigationParameter = pageState["SelectedItem"];
    }

    // TODO: Create an appropriate data model for your problem domain to replace the sample data
    var item = SampleDataSource.GetItem((String)navigationParameter);
    this.DefaultViewModel["Group"] = item.Group;
    this.DefaultViewModel["Items"] = item.Group.Items;
    this.flipView.SelectedItem = item;

    VirtualMachineDetails vmDet = new VirtualMachineDetails();
    var selectedVm = item.Title;
    if (selectedVm != "")
    {
        vmDet.VmName = selectedVm.ToString();
        var myFlipView = flipView as FlipView;
        var container = myFlipView.ItemContainerGenerator.ContainerFromItem(myFlipView.SelectedItem);
        var children = AllChildren(container);

        var vmStateTxtBox = children.OfType<TextBlock>().First(x => x.Name.Equals("tbStatus"));

        vmStateTxtBox.Text = await objService.GetVMStatusAsync(vmDet);
    }
}


public List<Control> AllChildren(DependencyObject parent)
{
     var list = new List<Control> { };
     for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
     {
         var child = VisualTreeHelper.GetChild(parent, i);
         if (child is Control)
         {
             list.Add(child as Control);
         }
         list.AddRange(AllChildren(child));
     }
     return list;
}

I get an error at the following line:

VisualTreeHelper.GetChildrenCount(parent)

Here's the error:

Can anyone point where I went wrong with the coding?

I referred to Jerry Nixon's article about accessing named control in a XAML in order to access the textblock in my flipview:

http://blog.jerrynixon.com/2012/09/how-to-access-named-control-inside-xaml.html

Thanks.