My b2evolution Version: 1.9.x

This has happened a couple of times now, it's beginning to bug me: I post a comment on my own blog, whilst signed in as myself (usually as a response to somebody else's comment), but after clicking "Send comment" and the page reloading, my comment hasn't been added.

The only way to get around this is to post something completely different, then edit the comment to be what I originally wanted, whereupon it will happily sit there with a spam karma of 0%

There's no error messages, there's nothing in my Antispam blacklist (it only has 2 entries so I know this to be true), I can't see any reasons for the comments to be refused.

How do I find out what problem b2 is having with these comments?