Browsers can be like squirrels in winter. During theming exercises, they horde your pages and this can drive engineers nuts. Expecting your error in the obvious places isn’t always that obvious.
There was an interesting post on the Mendix Forum yesterday, that caught me out. We suspected that the designer was making an error, while back at the ranch the issue was under the nose of the engineer trying out the new theme. Caching.
When working with new themes/skins, its best practice to clear your browser’s cache before using your new Mendix theme.
Alternatively, some browsers have a feature called incognito or private browsing. This separates your browsing session’s cache from your historical cache. It is a useful feature, not only when skinning, but when you accessing secure sites, like banking or using your friend’s browser while accessing your facebook account, but don’t want to leave any private data behind in his browser’s history and cache.