incomplete archives

Hello,

I noticed that my category and author archives seem incomplete. Specifically, they stop providing a ‘previously’ link after the 2nd or 3rd page. I can enter a page number directly in the url, which seems to work all the way to the first post. But an unsuspecting user will probably not notice.

Is this supposed to happen? If it is, is there a way to change it, so that all archive pages are easily accessible? If it is not, does anyone have an idea of what might be going wrong?

Thanks,
K