Bug on MasterDetailPage WP ?

Hi I try using MasterDetailPage using XAML.

It's work on android not on WP.

here the XAML :

<?xml version="1.0" encoding="utf-8" ?>

<MasterDetailPage.Master>

<ContentPage.Content>

  <Label Text="Food &amp; Drink:"
      Font="Large"
      XAlign="End" YAlign="Center" />
    </ContentPage.Content>
</ContentPage>

</MasterDetailPage.Master>

<MasterDetailPage.Detail>

<ContentPage.Content>

</ContentPage.Content>

</MasterDetailPage.Detail>

on WP I got this error : Text cannot be empty.

at Microsoft.Phone.Shell.ApplicationBarItemContainer.set_Text(String value)
at Microsoft.Phone.Shell.ApplicationBarItemContainer.UpdateProperties(Object sender, BoolEventArgs args)
at Microsoft.Phone.Shell.ApplicationBarIconButtonContainer.UpdateProperties(Object sender, BoolEventArgs args)
at Microsoft.Phone.Shell.ApplicationBarIconButtonContainer.BeginAttachToAppBar()
at Microsoft.Phone.Shell.ApplicationBarItemList

1.Insert(Int32 index, TApplicationBarItem item)
   at Microsoft.Phone.Shell.ApplicationBarItemList

1.System.Collections.IList.Add(Object value)
at Xamarin.Forms.Platform.WinPhone.Platform.UpdateToolbarItems()
at Xamarin.Forms.Platform.WinPhone.Platform.<.ctor>b__9(Object sender, EventArgs args)
at Xamarin.Forms.ToolbarTracker.EmitCollectionChanged()
at Xamarin.Forms.ToolbarTracker.set_Target(Page value)
at Xamarin.Forms.Platform.WinPhone.Platform.UpdateToolbarTracker()
at Xamarin.Forms.Platform.WinPhone.Platform.SetCurrent(Page page, Boolean animated, Boolean popping, Action completedCallback)
at Xamarin.Forms.Platform.WinPhone.Platform.SetPage(Page newRoot)
at Xamarin.Forms.Forms.ConvertPageToUIElement(Page page, PhoneApplicationPage applicationPage)
at fastVAT.WinPhone.MainPage..ctor()

Vincent