Semantic URL search (wp_rewrite->search_base)

Hi,

The thing is that I’m crazy with a problem in searchs …
I’m had a very simple code that made when searching for something in my wordpress, it’s automatically redirected to a semantic search url:

page.com/?s=term redirigía a page.com/results/term

And the code (so simply) it’s:

add_action('init', 'general_rewrites');

function general_rewrites() {
	global $wp_rewrite;

	$wp_rewrite->search_base = "results";
	$wp_rewrite->flush_rules();
}

This was working great, but suddenly stopped working … I’ve tried everything, I’ve even created a new installation without any code more than that on the default theme ‘twentythirteen’ but no way to get it working again …
Anyone have any idea what may be happening or what I should try?

Regards and thanks!