祖先模式下的DataTemplate绑定

Question

假设我们有以下代码：

MyGridViewColumn.xaml

<GridViewColumn x:Class="some_namespace.MyGridViewColumn"
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <GridViewColumn.CellTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type GridViewColumn}}, Path=MyString, Mode=OneTime"/>
        </DataTemplate>
    </GridViewColumn.CellTemplate>
</GridViewColumn>

MyGridViewColumn.xaml.cs

namespace some_namespace
{
    public partial class MyGridViewColumn
    {
        public MyGridViewColumn()
        {
            MyString = "Hello!";
            InitializeComponent();
        }

        public string MyString { get; set; }
    }
}

这感觉还可以，但它不起作用。什么是与＃34; MyString＆＃34;的正确绑定？