custom-background default-color not working

I am doing some theme maintenance on a few older themes and need to add support for custom backgrounds. I found that the default background color is not working by itself. I mages work fine with this code, however, the color is not changing (nor does it work as a stand-alone default).

Is this a bug? I have tested on v3.9 and other themes with the same problem.

add_action( 'init', 'theme_custom_background');

function theme_custom_background(){
	$images_path = get_stylesheet_directory_uri().'/images';

	$theme = genesis_get_option('bf_style_selection');

	switch ($theme) {
		case 'bf-blue':
			$bg_color = 'def1fc';
			$bg_image = $images_path.'/header-bg-blue.gif';
			break;
		case 'bf-black':
			$bg_color = 'dadada';
			$bg_image = $images_path.'/header-bg-black.gif';
			break;

	}

	$defaults = array(
	'default-color'          => $bg_color,
	'default-image'          => $bg_image,
	'default-repeat'         => 'repeat-x',
	'default-position-x'     => 'top',
	);

	add_theme_support( 'custom-background', $defaults);
}