limit 0,10 within SELECT ..... FROM ......

I run PostgreSQL and have some questions:

How come
$query = "SELECT id, tittel, dato, kilde, referat FROM nyheter order by id desc limit 0,10";
Does not display any posts in my news script, but
$query = "SELECT id, tittel, dato, kilde, referat FROM nyheter order by id desc limit 10";
Shows the last 10.?

And:

How come
$query = "SELECT id, tittel, dato, kilde, referat FROM nyheter order by id desc limit 10,20";
Displays posts 5 to 14, and not 10 to 20?!

Regards

Paul Ottar Tornes