I have a client that uses a CDN to fill images, from a sub domain ( images.domain.com). We've made sure that the sub domain itself is not blocked. We've added a robots.txt file, we're creating an image sitemap file & we've verified ownership of the domain within GWT. Yet, any crawler that I use only see's the first page of the sub domain (which is .html) but none of the subsequent URL's which are all .jpeg. Is there something simple I'm missing here?