exclude categories not working

tried to follow this post: http://wordpress.org/support/topic/exclude-posts-from-wp_query

but no luck, doesn’t seem to exclude the categories in that category. any ideas?

here is the code:

<?php
            /*start lukasz edit to exclude cats */
            $args=array(
			  'category__not_in' => array(125),
			);
			$query = null;
			/* end lukasz edits */ 

			$query = new WP_Query($args); /* lukasz: added $args in query, take out of errors*/
			$query->query('posts_per_page='. $number );
			while ($query->have_posts()) : $query->the_post();
			?>