Go to first unread post in thread '{1}' - non-canonical redirect

[forums55]

I use canonical links on my vB 4.2.2 forum

On the home page, when I click on the Last post link (Go to first unread post in thread {1}), the link appears like this:

http://www.website.com/forum-name/51-thread-name-new-post.html

When the redirect is done however, the link is non-canonical (showthread.php etc etc etc)

The "Go to last post" arrow works just fine redirecting to canonical link.

How can I solve the redirect of "Go to first unread post in thread {1}" to lead to a canonical URL?

Thanks.