Show author name?

which template did you edit?

can you post the code where you inserted this snippet?
(please use the pastebin)

http://codex.wordpress.org/Function_Reference/the_author

you added the code outside the loop, i.e somewhere before
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

some of the template tags are a bit tolerant to the this, even if the results might be unpredictable – the_author() seems to definitely need to be in the loop.

try to re-shuffle the code:
http://wordpress.pastebin.com/SwssBBAX