For me it looks like a permission problem. Could you please check and make sure that users have Use Social Feature
permission.
check this blog
[http://mysharepointwork.blogspot.com/2010/11/disablehide-social-tags-notes-for-group.html][1]http://mysharepointwork.blogspot.com/2010/11/disablehide-social-tags-notes-for-group.html
good to know blog:
http://www.c-sharpcorner.com/uploadfile/anavijai/tags-and-notes-in-sharepoint-2010/
[1]: http://mysharepointwork.blogspot.com/2010/11/disablehide-social-tags-notes-for-group.html