Change key baised style in silverlight

Question

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

<ResourceDictionary

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

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

<Style TargetType="Button" x:Key="s1">

<Setter Property="Background" Value="Red"/>

<Setter Property="Foreground" Value="Red"/>

</Style>

</ResourceDictionary>

Dictionary2.xaml

<ResourceDictionary

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

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

<Style TargetType="Button" x:Key="s1">

<Setter Property="Background" Value="Green</Setter>

<Setter Property="Foreground" Value="Green"></Setter>/>

</Style>

</ResourceDictionary>

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

<Grid x:Name="LayoutRoot" Background="White">

<Button Style="{StaticResource s1}" Content="Button" HorizontalAlignment="Left" Margin="195,133,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>

</Grid>

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);

}