How can I get rid of the border around the image embedded button?

I am trying to get rid of the white border around the button. I am adding pictures to it Button. It doesn't seem to be the button itself, but the border of the image.

Here is the XAML,

   <Style x:Key="MyButton" TargetType="Button">
        <Setter Property="OverridesDefaultStyle" Value="True" />
        <Setter Property="Cursor" Value="Hand" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border Name="border" BorderThickness="0" Background="{TemplateBinding Background}" CornerRadius="5" >
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" />
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter Property="Opacity" Value="0.5" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

and Buttonitself

   <Button Name="Button2" Content="stuff" Height="25" Grid.Column="1" Grid.Row="1"
          Style="{StaticResource MyButton}" Click="Button2_OnClick">
              <Button.Background>
                  <ImageBrush ImageSource="Images\ButtonEnterLight.png"></ImageBrush>
              </Button.Background>
   </Button>

The result is this

What else do I need to do to make it go away? It's been bugging me for the last week.

Edit: Here's a screenshot of the live visual tree, expanded to the first button with an image embedded in it.