BuddyPress.org

Finally I got it working

Well first add the lines from this patch https://trac.buddypress.org/ticket/1426 to bp-core/bp-core-catchuri.php

and then go to bp-core.php and in line 95 put the code like this (note the index.php) $bp->root_domain = bp_core_get_root_domain() . '/index.php';

Well, also, I have a custom template, and in my navigation I have manually put the links in the header to look like this: <li><a href="http://yourdomain.com/wordpress/index.php/activity/" title="Actividad">Actividad</a></li> but it probably works also in the bp-default theme.

So, hope this help someone