What's wrong with this script?

PHP Code:
if(isset($_GET['cat'])) {
 
$query mysql_query("SELECT * FROM nb_posts WHERE category='".$_GET['cat']."'");
} else if(isset(
$_GET['user'])) {
 
$query mysql_query("SELECT * FROM nb_posts WHERE author='".$_GET['user']."'");
} else {
 
$query mysql_query("SELECT * FROM nb_posts");

Everything about it works, except for the ELSE part.

The script is supposed to display a list of posts. I've made a filter system, using Categories ('cat') or Users ('user'). If either of those is set, it returns the rows with the appropriate values, but if neither of them is set, it returns nothing.