After reading a lot about that issue I have found a page where it refers to that problem. It seems to be a wordpress problem.
http://stylizedweb.com/2008/08/13/query_posts-pagination-problem/
Many comments seem to be happy with the solution.
As it is refered as a solution in here: https://wordpress.org/support/topic/wp-30-bug-with-pagination-when-using-static-page-as-homepage-1
So in that first web it says you have to replace code:
<?php if (have_posts()) : ?>
<?php query_posts(“category_name=somecat”); ?>
<?php while (have_posts()) : the_post(); ?>
replace with
<?php if (have_posts()) : ?>
<?php $paged = (get_query_var(‘paged’)) ? get_query_var(‘paged’) : 1; query_posts(“category_name=somecat&paged=$paged”); ?>
<?php while (have_posts()) : the_post(); ?>
The thing is I don´t find where I should make the code change for that to work.
It is possible this solves this problem?