I have a UserControl which contains a listbox and few buttons.

<UserControl x:Class="ItemControls.ListBoxControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
    <Grid>
        <ListBox:ExtendedListBox SelectionMode="Single" ItemsSource="{Binding LBItems}" Height="184">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <CheckBox Content="{Binding}"/>
                    </DataTemplate>
                </ListBox.ItemTemplate>
        </ListBox>
<Button Command="RemoveCommand"/>
</Grid>
</UserControl>

And the code behind:

public static readonly DependencyProperty RemoveCommandProperty =
 DependencyProperty.Register("RemoveCommand", typeof(ICommand), typeof(ListBoxControl), null);

 public ICommand RemoveCommand
 {
  get { return (ICommand)GetValue(RemoveCommandProperty); }
  set { SetValue(RemoveCommandProperty, value); }
 }

 public static readonly DependencyProperty LBItemsProperty =
 DependencyProperty.Register("LBItems", typeof(IEnumerable), typeof(ListBoxControl), null);

 public IEnumerable LBItems
 {
  get { return (IEnumerable)GetValue(LBItemsProperty); }
  set { SetValue(LBItemsProperty, value); }
 }

I'm using this control in the view like this:

<ItemControls:ListBoxControl Height="240" Width="350" LBItems="{Binding Items, Converter={StaticResource ItemsConverter}, Mode=TwoWay}" RemoveCommand="{Binding RemoveCommand}"/>

The command works fine, though the listbox binding doesn't. My question is - WHY?