Binding in WPF style causes inexplicable "Cannot find governing FrameworkElement" error

I have an ItemsControl that displays a bunch of rectangles. Each rectangle needs to be offset upward and to the left. So, I created a RectangleStyle that uses bindings to set the width, height, X translation, and Y translation for a rectangle.

The width and height bindings are working fine, but I'm getting the following error for the TranslateTransform bindings:

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=Offset.X; DataItem=null; target element is 'TranslateTransform' (HashCode=16452547); target property is 'X' (type 'Double')

Here is the definition of my ItemControl:

<ItemsControl
    Style="{StaticResource ItemsControlStyle}"
    ItemsSource="{Binding Zones}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Rectangle Style="{StaticResource RectangleStyle}" />
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

Here is the definition of ItemsControlStyle:

<Style x:Key="ItemsControlStyle" TargetType="ItemsControl">
    <Setter Property="ItemsPanel">
        <Setter.Value>
            <ItemsPanelTemplate>
                <Canvas />
            </ItemsPanelTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="ItemContainerStyle">
        <Setter.Value>
            <Style>
                <Setter Property="Canvas.Left" Value="{Binding Point.X}" />
                <Setter Property="Canvas.Top" Value="{Binding Point.Y}" />
            </Style>
        </Setter.Value>
    </Setter>
</Style>

And here is the definition of RectangleStyle:

<Style x:Key="RectangleStyl