When i dpm that $vars, in classes key, there is no r_style class, whyyyy? I tried clear cache through devel module, but still the same, what i am doing wrong?

name = JH Template
core = 7.x
engine = phptemplate

styles[all][] = css/style.css
settings[bg_style] = 'r_style'

theme-settings.php

function jh_process_html(&$vars) {
    $vars['classes'] .= ' ' . theme_get_setting('bg_style');
    dpm($vars); // in classes string isn't r_style class
}

EDIT: the real question is, why theme_get_setting('bg_style') returns NULL