Pier blog and permissions

Hi, I was totally confused about my blog today. I always expected that people can comment on blog posts. Having a look today first showed that there was no entry form for entering a comment. I started to fiddle around with the permissions on the blog page but this was kinda strange. As soon as I added the "Add commment" permission to others a link "add" was added at the bottom beside login and view. Clicking on the link opened the normal add command that would let me add post, component,... Removing the permission again removed the link again. I know this sounds strange and I'm also sure that it is probably not what really happened. Now it is so that only the first post has the comment add form and no other post. Well, it is the only one in this month so it could also be that. Aren't all blog post supposed to be commentable? thanks, Norbert