In a Silverlight application, create a button and drop a Frame control. If you set the Source property of this Frame control to another page (let's say "/anotherpage.xaml") in design time it will work just fine when you execute this application. But if you want to navigate to a different page using code you may write a code that looks like this…

private void btnNavigate_Click(object sender, RoutedEventArgs e){    
     frame1.Source = (new Uri("/anotherpage.xaml");
}

If you execute your application it will error out, saying…

Invalid URI: The format of the URI could not be determined.

To get rid of this problem, use the following code…

private void btnNavigate_Click(object sender, RoutedEventArgs e){
    frame1.Source = (new Uri("/anotherpage.xaml", UriKind.Relative));
}

Cheers,
Rahul