I am trying to bind Content Control Items control to Tab Item Header but not working, how can I bind rightly.

I want to bding Path=Items.Count to Texblock in TabItem Header Template

```
<TabControl>
    <TabItem>
        <ContentPresenter Content="{Binding Items, Mode=OneTime}">
            <ContentPresenter.ContentTemplate>
                <DataTemplate>
                    <ListBox ItemsSource="{Binding}"/>
                </DataTemplate>
            </ContentPresenter.ContentTemplate>
        </ContentPresenter>
        <TabItem.HeaderTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="Item Count"/>
                    <TextBlock Text="{Binding Path=Items.Count, RelativeSource={RelativeSource FindAncestor, AncestorType=ContentControl}}"/>
                </StackPanel>
            </DataTemplate>
        </TabItem.HeaderTemplate>
    </TabItem>        
</TabControl>

```

**Code Behind**

```
public partial class MainWindow : Window
    {
        private static ObservableCollection<string> items;
        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
            items = new ObservableCollection<string>();
            items.Add("test1");
            items.Add("test2");
            items.Add("test3");
            items.Add("test4");

        }
        public static ObservableCollection<string> Items
        {
            get { return items; }
        }
    }

```