New Post: CheckComboBox and [Flags] enum

I'm using Xceed Extended WPF Toolkit to display a enum with [Flags] attribute in a PropertyGrid

[Flags]
public enum TestEnum
{

Test1 = 1,
Test2 = 2,
Test3 = 4,
Test4 = 8,
Test5 = 16,
Test6 = 32,
Test7 = 64,

}

Because I can't know the enum definition at compile time, I would dynamically create an Enum using EnumBuilder. ( I can't rely on a compile-time enum. I would dynamically create an Enum using [EnumBuilder])

I created an editor to display the enum as CheckComboBox:

public class CheckComboBoxEditor : TypeEditor<CheckComboBox>, ITypeEditor
{

protected override void SetValueDependencyProperty()
{
    ValueProperty = CheckComboBox.SelectedValueProperty;
}

protected override CheckComboBox CreateEditor()
{
    return new CheckComboBox();
}

protected override void ResolveValueBinding(PropertyItem propertyItem)
{
    var _binding = new Binding("Value");
    _binding.Source = propertyItem;
    _binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
    _binding.Mode = BindingMode.TwoWay;
    _binding.Converter = CreateValueConverter();
    BindingOperations.SetBinding(Editor, CheckComboBox.SelectedValueProperty, _binding);

    var _binding2 = new Binding("Value");
    _binding2.Source = propertyItem;
    _binding2.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
    _binding2.Mode = BindingMode.TwoWay;
    _binding2.Converter = CreateValueConverter();
    BindingOperations.SetBinding(Editor, CheckComboBox.SelectedItemProperty, _binding2);

    Editor.ItemsSource = Enum.GetValues(propertyItem.Value.GetType());
}

}

As you can see, so far I've tried to bind each the SelectedValue and the SelectedItem property. CreateValueConverter() is defined in the base class and returns null.

It works well if I select some Values in the box and hit my save Button - in my model, I receive the correct enum value. But it doesn't work in the other direction - if i set any enum value (with or without flags) to my property, all values are unchecked and the content area is empty.

Do you have any idea to solve this problem?