Finally found why this is happen... i've used the previous WordPress installation. It doesn't support the function,,, Then, i tried to implement it in the latest WP version, 3.5.2, it works like a charm!
I think, it happen because wordpress doesn't recognize the function needed by the simple-fields, by default defined at /wp-includes/cache.php.. hope it help you guys, who have the same problem.
it's a small problem if you just developed it in a new installation, but when it comes to a well running production sites, consider to migrate first to the latest version before implementing it.
My Labs : WP3.5.2 + Simple_fields 1.4.1 + XAMPP