Hi Cristiano,
Thank you for your question.
Not surprisingly,this plugin won’t work with many themes. because this plugin is only designed for the standard wordpress theme. As I stated in the plugin description, this plugin is totally depend on your website theme. if the CSS in comment section in the single page has bee changed, then it will probably not work with your theme.

I will release a new version soon, which hopefully the AJAX posting will work with all themes, but comment pagination is not guaranteed.