Why do next pages load the same content rather then older articles?

Are you using 'posts_per_page' and 'paged' in the query string? if not try to add

$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
$query .= 'posts_per_page=5&paged='.$paged

Number 5 will be replaced with the number of posts after which you want the next page (pagination) link to show up.

Also remove the if statement on the next page link

if ( $wp_query->max_num_pages > 1 )