Add custom button to "Picture Tools" contextual tab.

Hi,

I'm trying to add custom button to "Picture Tools" contextual tab which is available when you click on the image in rich text field.

<CustomAction Id="TestButton" Location="CommandUI.Ribbon"><CommandUIExtension><CommandUIDefinitions><CommandUIDefinition Location="Ribbon.Image.Image.Properties.Controls._children">
<Button
            Id="TestButton"
            Command="ShowAlert"
            Image16by16="/_layouts/images/actionseditpage16.gif"
            Image32by32="/_layouts/images/actionssettings.gif"
            LabelText="Custom Script"
            Sequence="10"
            TemplateAlias="o1"/>
</CommandUIDefinition></CommandUIDefinitions><CommandUIHandlers><CommandUIHandler Command="ShowAlert" CommandAction="javascript:alert('Custom Script');" /></CommandUIHandlers></CommandUIExtension></CustomAction>

but action not appearing on in the ribbon. The same code works if i change location to "Ribbon.EditingTools.CPEditTab.Paragraph".

How can i add custom button to "Picture tools" contextual tab of the ribbon?

Best regards, Chernobrivets