Lightbox2 Integration

I am having trouble getting the wicketstuff Lightbox2 plugin integration
working. I am using the basic example with image resources at the
bottom of
https://github.com/wicketstuff/core/wiki/Lightbox2-Plugin-Integration.
The thumbnail displays just fine, but when I click on the thumbnail only
the mask for the page shows up and the image is missing. Does anybody
have this plugin working? The examples don't seem to work for me either
(6.15.0). I tried adding "data-lightbox" attribute per the
(http://lokeshdhakar.com/projects/lightbox2/) website, but it didn't
seem to help. Here is my code where res is an instance of a class that
holds the ResourceReferences:

add(new LightboxLink("imageLink", res.getFullImage()) {
private static final long serialVersionUID = 1L;

@Override
protected void onComponentTag(ComponentTag tag)

super.onComponentTag(tag);
tag.put("data-lightbox", getMarkupId());

}.add(new Image("imageFile", res.getThumbnail())));