Hi Fabio,
This issue occur on your site or on https://community.moosocial.com ?
If on your site please submit a ticket, we will help you to check it.
If it occur on https://community.moosocial.com ? please tell me know which blog you shared to get this message?
Please help me check this issue on English language. It is working well right? if yes, maybe translate file on Italian language got a issue, we will check it.
im sure the code is correct, but why i see /users/view/1/activity_id:4 and not the username?!