unable to stop the animation rotation on button click in c#

<Window x:Class="rotat.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">

    <Window.Resources>
        <Storyboard x:Key="sbdRotation"  RepeatBehavior="Forever">
            <DoubleAnimation
            Storyboard.TargetName="image"
            Storyboard.TargetProperty="(Image.LayoutTransform).(RotateTransform.Angle)"
            From="0" To="360"   Duration="0:0:0:1" FillBehavior="Stop"/>
        </Storyboard>

    </Window.Resources>

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>

        <Image Name="image" Width="50" Height="50" Source="C:\Users\shreddy.FAREAST\Pictures\disk1.png">
            <Image.LayoutTransform>
                <RotateTransform CenterX="0.5" CenterY="0.5" />
            </Image.LayoutTransform>
        </Image>

        <Button Grid.Row="1" Content="Rotate the image!" Click="Button_Click" Width="100" Height="100" Margin="106,30,311,29" />
        <Button x:Name="stop" Width="100" Height="100" Margin="308,20,109,39" Grid.Row="1" Click="stop_Click" Content="stop"/>
    </Grid>
</Window>

public MainWindow()
     {
         InitializeComponent();
         sd = new Storyboard();
         sd = (Storyboard)FindResource("sbdRotation");
     }
     public void Button_Click(object sender, RoutedEventArgs args)
     {

         //while (mn>0)
         //{

             sd.Begin(this);
             mn--;
             d++;
        // }
     }

     private void stop_Click(object sender, RoutedEventArgs e)
     {
         sd.Stop(this);
     }