Why is my URI messed up when using NavigationService?

A "simple" situation:

Assembly1 contains:

• A couple of WPF Pages (.xaml)

Calling Assembly contains:

• A WinForm with an ElementHost
• The ElementHost contains a WPF UserControl that has a single Frame (=MainFrame)

The WinForm uses the NavigationService from the MainFrame to navigate to an absolute Uri in a like this:

NavigationService.Navigate(new Uri("pack://application:,,,/Assembly1;component/Page1.xaml", UriKind.Absolute);

Navigated page is displayed, all fine until now. Now when I look at the NavigationService.CurrentSource (which is the Uri of the currenlty loaded page) it looks like this:

All kinds of Exceptions...And what is also weird is that the property IsRelative is True and the OriginalString property states : "/Assembly1;component/Page1.xaml". The whole "pack-part" is lost. So when using the Uri again (what i would like) results in errors because this Uri d开发者_高级运维oesn't give me a correct path anymore.

Am I missing some essential part of the NavigationModel in WPF? Any help would be appreciated!

What I choose as a solution is to pick up the

NavigationService.CurrentSource

and paste the "pack-part"in front of it again. Then use it again for navigation.