Change key baised style in silverlight

I have two styles in two resource dictionaries. When application load then I have loaded one (`Dictionary1.xaml`) resource. After that when I click on button then I want to change style. i.e I want to load `Dictionary2.xaml`. I have changed but there is no effect on my button.

Dictionary1.xaml

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

Dictionary2.xaml

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

When application load then

Uri sUri = new Uri("/KeyCheck;component/Dictionary1.xaml", UriKind.Relative);

ResourceDictionary r = new ResourceDictionary();

r.Source = sUri;

Resources.MergedDictionaries.Add(r);

Apply style in page: Main.xaml

When click on button then:

private void Button_Click(object sender, RoutedEventArgs e)

{

Uri sUri = new Uri("/KeyCheck;component/Dictionary1.xaml", UriKind.Relative);

ResourceDictionary r = new ResourceDictionary();

r.Source = sUri;

App.Current.Resources.MergedDictionaries.Remove(r);

sUri = new Uri("/KeyCheck;component/Dictionary2.xaml", UriKind.Relative);

r = new ResourceDictionary();

r.Source = sUri;

App.Current.Resources.MergedDictionaries.Add(r);

}