Enqueueing IE conditional stylesheets in WordPress the right way - css

Question

I know this question has been asked before on stackoverflow, but for the life of me I cannot get my conditional stylesheet to load and work for all versions of IE. I appreciate any help given in advance, it's really been getting to me, and I'm not sure what to do from here. I also tried loading the IE stylesheet in the header but that didn't seem to work either. My theme is not a child theme.
Here's my functions code:
function theme_styles() {
global $wp_styles;
wp_enqueue_style( 'bootstrap_css', get_template_directory_uri() . '/css/bootstrap.min.css' );
wp_enqueue_style( 'glyphicons_css', get_template_directory_uri() . '/css/glyphicons.css' );
wp_enqueue_style( 'glyphiconssocial_css', get_template_directory_uri() . '/css/social.css' );
wp_enqueue_style( 'main_css', get_template_directory_uri() . '/style.css' );
/**
* Load our IE-only stylesheet for all versions of IE:
* <!--[if IE]> ... <![endif]-->
*
* NOTE: It is also possible to just check and see if the $is_IE global in WordPress is set to true before
* calling the wp_enqueue_style() function. If you are trying to load a stylesheet for all browsers
* EXCEPT for IE, then you would HAVE to check the $is_IE global since WordPress doesn't have a way to
* properly handle non-IE conditional comments.
*/
wp_enqueue_style( 'ie_css', get_template_directory_uri() . '/ie.css', array('bootstrap_css', 'main_css') );
$wp_styles->add_data( 'ie_css', 'conditional', 'IE' );
} add_action( 'wp_enqueue_scripts', 'theme_styles' );

Answer 1

That method works fine. Note that commented styles seem to be invisible in FF Firebug, in Chrome developer tools on the other hand they are displayed.
add_action( 'wp_enqueue_scripts', 'so27214782_wp_enqueue_scripts' );
function so27214782_wp_enqueue_scripts()
{
global $wp_styles;
wp_enqueue_style( 'so27214782_ie', get_template_directory_uri() . '/ie.css', array(), '27214782', 'all' );
$wp_styles->add_data( 'so27214782_ie', 'conditional', 'IE 6' );
}

Answer 2

I don't see anything that might hamper your function. Here is how twentyfourteen load the conditional stylesheet
// Load the Internet Explorer specific stylesheet.
wp_enqueue_style( 'twentyfourteen-ie', get_template_directory_uri() . '/css/ie.css', array( 'twentyfourteen-style', 'genericons' ), '20131205' );
wp_style_add_data( 'twentyfourteen-ie', 'conditional', 'lt IE 9' );