style trigger on .Net 4.5 RibbonToggleButton SmallImageSource

Question

I have the following Style for my RibbonToggleButton

                <Style TargetType="RibbonToggleButton">
                <Style.Triggers>
                    <Trigger Property="ToggleButton.IsChecked" Value="True">
                        <Setter Property="SmallImageSource" >
                            <Setter.Value>
                                <Image Source="Images/small_checked.png"/>
                                </Setter.Value>
                        </Setter>
                    </Trigger>
                    <Trigger Property="IsChecked" Value="False">
                        <Setter Property="SmallImageSource" >
                            <Setter.Value>
                                <Image Source="Images/small_unchecked.png"/>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </Style.Triggers>
            </Style>

I also tried the full path for the SmallImageSource property:

 "System.Windows.Media.ImageSource.SmallImageSource"

But i always get this error:

Error 1 Cannot resolve the Style Property 'SmallImageSource'. Verify that the owning type is the Style's TargetType, or use Class.Property syntax to specify the Property. Line ....

Update "Solution"

<RibbonToggleButton.Style>
    <Style>
        <!-- set the affected properties only here -->
        <Setter Property="SmallImageSource" Value="Images/small_unchecked.png"/>
        <Setter Property="LargeImageSource" Value="Images/large_unchecked.png"/>
        <Style.Triggers>
            <Trigger Property="IsChecked" Value="True">
                <Setter Property="SmallImageSource" Value="Images/small_checked.png"/>
                <Setter Property="LargeImageSource" Value="Images/large_checked.png"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</RibbonToggleButton.Style>

Answer 1

Have you tried adding a target type to your style?

So it would be <Style TargetType="RibbonToggleButton">instead of just <Style>