Cannot find governing FrameworkElement or FrameworkContentElement

[stofel]

Hi, I'm a newbie in wpf and I have a problem with the binding. I have a class inherited from FramworkElement and there is a Collection. The Items of this collection are inherited from DependencyObject. On the Form is only one TextBox. I want that the text, which is typed by the user will be copied into the first Item of the collection. Here some code

public class Item: DependencyObject
{
public string Name { get; set; }

      public virtual object Value {
        get { return GetValue(ValueProperty); }
        set { SetValue(ValueProperty, value); }
    }

    #region DependenvyProperty
      public static readonly DependencyProperty ValueProperty =
          DependencyProperty.Register("Value", typeof(object), typeof(Item));
    #endregion

}

public class ItemContainer : FrameworkElement
{
   
    private List<Item> \_itemlist = new List<Item>();

    public List<Item> ItemList
    {
        get { return \_itemlist; }
    }
}

and the form:

Window x:Class="WpfApplication2.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="417" Width="589" xmlns:my="clr-namespace:WpfApplication2">
<Grid>
<my:ItemContainer Height="18" HorizontalAlignment="Left" Margin="-168,0,0,33" x:Name="itemContainer1" VerticalAlignment="Bottom" Width="18">
my:ItemContainer.ItemList
<my:Item Name="Item1" Value="{Binding ElementName=txtItem1, Path=Text}" />
<my:Item Name="Item2" />
</my:ItemContainer.ItemList>
</my:ItemContainer>
<Canvas Margin="16,18,8,6" Name="canvas1">
<TextBox Canvas.Left="88" Canvas.Top="15" Height="23" Name="txtitem1" Width="89" />
<Label Canvas.Left="14" Canvas.Top="16" Height="22" Name="label1" Width="58">Item1
</Label>
</Canvas>
</Grid>
</Window>

At runtime the program displays the error2 Cannot find governing FrameworkElement or FrameworkContentElement. I don't want to inherit item from FrameworkelElement because in the real project the class Item is inherited from another class. What can I do to transfer the text from the textbox to the first item of the collection ? Thanks in Advance