What "tutorial"? I have no idea what you're talking about.
The opening page calls the collection "WordPress Lessons" and that makes it a tutorial in my English.
But I will gladly call it "lessons" if you prefer the term.
That snippet pretty much exactly agrees with what I said. posts_nav_link() is used on pages other than the single post pages.
Strange. The "such as" in my quote does not mention pages with posts on them, it limits the use of post_nav_link to "categories, archives, searches, and the index page".
posts_nav_link() is used on pages other than the single post pages. Those tend to use previous_post and next_post.
I understand "single post pages" to refer to pages with permalinks, i.e. pages carrying the owner's dated posts. I have had WordPress for only 3 days so I am still finding my way with the terminology which seems to be quite clear in this area:
Previous_post: "Used on single post/permalink pages, this tag lists the previous post in chronological order from the current post."*** (Next_post is similar).
Post_nav_link: "For the index, category, and archives, use the posts_nav_link() tag."***
Then I'd say you're doing something else wrong. If it works in the default theme but not in your theme, then I'd say one of the differences between these themes is causing the problem, eh?
I would gladly agree with you but for the fact that I am unable to detect any difference. In any event, I have tried all the permutations and combinations I could think of but that did not help. I must confess that it did cross my mind that this is a phenomenon peculiar to version 2.0.4.
No, it's a sign that people have not read the codex on the subject, despite the many links posted that point to it.
Quite possibly, but that does not apply to me because I have read them all, word by word, and have followed the syntax to the letter, comma, and all the others.
Certainly in the first one you cite (post_nav_link) it says only "There is currently no text in this page" so reading it helps little. There is another that you didn't mention but from which I quoted (Next_and_Previous_Links) and that gives the syntax for previous_post as:
<?php previous_post(); ?>
with parameters: format, text and title, i.e. effectively:
<?php previous_post('format', 'previous', 'title'); ?>
whereas in the document previous_post the syntax is given as:
<?php previous_post('format', 'previous', 'title', 'in_same_cat', limitprev, excluded_category); ?>
which is quite a difference. That is what I meant by "contradictions".
Nevertheless, I have tried all of them and not one of them works for me so, as you say, the question is: "What am I doing wrong?"
I notice that there are other questions from people with a similar problem so I just might not be alone.