Adding a BindableProperty to my CustomViewCell? Where to call SetBinding?

I have a CustomViewCell with controls that are bound to my model object -- that works fine. What I'm trying to do now is add a bindable ListItemType property to my CustomViewCell so I can display multiple kinds of cells in one ListView. Here is my code:

public enum ListItemType 
{
    Header = 0,
    Data = 1
}

In my CustomViewCell I add the BindableProperty:

   public static readonly BindableProperty ListItemTypeProperty =
        BindableProperty.Create<CustomViewCell,ListItemType> (
            p => p.ListItemType, ListItemType.Header);

    public ListItemType ListItemType 
    {
        get { return (ListItemType)GetValue(ListItemTypeProperty); }
        set { SetValue(ListItemTypeProperty, value); }
    }

And in the constructor I set the binding:

public CustomViewCell()
{
    SetBinding(CustomViewCell.ListItemTypeProperty, new Binding("Type"));
...
}

The binding isn't working though. If I set a breakpoint on ListItemType property it never reaches it. As a test, I created a binding on a Label control like so, and the ListItemType would display correctly meaning the first cell would display Header and the remaining cells display Data.

 var typeLabel = new Label();
 typeLabel.SetBinding(Label.TextProperty, new Binding("Type"));

How can I properly set up a binding to a property within my ViewCell?