It's FI and New Member's Section that don't count post count. The ways that your post count would not go up or even down is because one of the following reasons:
1) You posted in those sections.
2) The thread was moved to one of those sections.
3) Your post was deleted.
4) The thread was deleted.
5) The thread was moved to the trash bin.
Those are the ways that your post count would have gone down or not moved. Let's say you posted in the KH area, so your post count would go up one. If that thread was moved to say, FI, then your post count would go back down.
Since this is a question answered an awful lot, I'll just close this.