Style property trigger for button

<Window x:Class="WpfApplication1.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>
        <Style TargetType="Button">
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Content">
                        <Setter.Value>
                            <Image Source="Images\B.jpg"></Image>
                        </Setter.Value>
                    </Setter>

            </Trigger>
                <Trigger Property="IsMouseOver" Value="false">
                <Setter Property="Content">
                        <Setter.Value>
                            <Image Source="Images\A.jpg"></Image>
                        </Setter.Value>
                    </Setter>
            </Trigger>
            </Style.Triggers>

        </Style>
    </Window.Resources>
    <Grid>
        <Button Margin="70,53,61,58"/>
    </Grid>
</Window>

Regards,
Selva Ganapathy K