Hi Andrea,
The first thing to do is visit Events → Settings → Display and double check that Photo View is enabled – even if it is, it may be worth re-saving that very page and then continue to WordPress’s Permalink Settings screen: you don’t need to change anything here, however, as simply visiting this screen “flushes” various rules.
Last but not least, if you have a caching plugin enabled please clear the cache. Hopefully the photo view will then work as expected — but if not, please simply post a new topic here on the forums and one of the team will be happy to assist further (however as we try hard to stick to one issue per topic I will at this point close out this one).
Thanks again!