I needed to add blog posts from a Tumblr blog to a new installation. I wanted the dates to be the same as the creation dates (most from 2011) so I downloaded the latest version of Datechanger I could find, which was 2.1. Once I installed it, known of the new entry buttons at the bottom of the post would work. I tried version 2.0 with the same result. FlatPress version is latest 1.0 release.
Could the fact that the language was Italian be the difference?