Older entries link not working

Hello, I hope somebody can tell me what is wrong here.
I have a website https://www.agescibologna.it run with twentyeleven theme. When I click on”older post” link at the bottom of the page, which brings me to: mysite/blog/page/2/. But this shows me the exact same 7 posts as the previous page (mysite/blog/). What can I do?