Component is null in mixin

[Lance Java]

My last post did not get a response so perhaps including some code might
help.
I have a mixin which I attach to a custom component but the component is
null in the afterRender method of my mixin

It appears that @InjectContainer is not working... is there something I need
to add to my component? (MixinAny)

/**
 * This class is like the standard Any component except it supports
getClientId() for use in mixins
 */
@SupportsInformalParameters
public class MixinAny implements ClientElement {
    @Inject
    private ComponentResources resources;

    @Inject
    private PageRenderSupport support;

    private String clientId;

    @Mixin @SuppressWarnings("unused")
    private DiscardBody discardBody; // I copied this from the Field
component looking at the autocomplete mixin

    @Mixin @SuppressWarnings("unused")
    private RenderInformals renderInformals;

    @BeginRender
    protected void beginRender(MarkupWriter writer)
    {
        clientId = support.allocateClientId(resources);
        writer.element(resources.getElementName(null));
        writer.attributes("id", getClientId());
        resources.renderInformalParameters(writer);
    }

    @AfterRender
    protected void afterRender(MarkupWriter writer)
    {
        writer.end(); // the element
    }

    /**
     */
    public String getClientId() {
        return clientId;
    }
}


@IncludeJavaScriptLibrary({
    "context:/layout/javascript/jquery.js",
    "context:/layout/javascript/interface.js"
})
@MixinAfter
public class SortableTarget {
    private static final Logger LOGGER =
Logger.getLogger(SortableTarget.class);

    @Parameter(defaultPrefix = TapestryConstants.LITERAL_BINDING_PREFIX)
    private String accept; // this is populated

    @InjectContainer
    private ClientElement container; //This should be my MixinAny component
but is null

    @Inject
    private PageRenderSupport renderSupport; // this is populated

    @AfterRender
    public void afterRender() {
         // container is null here
    }
}

Cheers,
Lance.