When I click your link, I am taken to this page:
http://aarinfantasy.com/forum/blogs/.../index893.html
I went through the blog archive to find the oldest blog, and the link (in the calendar) also led me to the same post as the "index893" link.
I don't know where the "...index965.html" link can be seen in the forum itself, but it may be that some blogs were deleted since this function was introduced to the forum? In which case, it would explain why the link you give is being automatically redirected to one with a lower index number.