Restoring a backup - something went wrong, need help!

I'm having some trobule getting a backup to work. I reinstalled my server and the forum installation is gone so I have a freshly installed PunBB and my SQL-file. The SQL-file is called punbb.sql and my database is called punbb.
The first thing I did was to create the punbb database and install punBB using this database. After that I uploaded my punbb.sql to my server and did a: rdj@server:~$ mysql -p -u mysqluser punbb < punbb.sql. This works fine and my forum looks like normal. When I try to post i got an error message that I solved using this script found at these boards.

<?PHP
define('PUN_ROOT', './');
require PUN_ROOT.'include/common.php';

$db->query('UPDATE '.$db->prefix.'users SET last_post=0');
?>

Then posting seemed to work. But whenever I create a new topic everything looks normal but when the redirecting is done and I'm back at the view topic page again the new post wont show. It's gone. Cant fint it anywhere. But if I choose to reply to an already existing post, everything works fine.
So... What have I done wrong when I restored my backup? A forum where users cant post new posts and only reply to existing posts will become quite boring after a while.
any ideas?