My RSS Feed doesn’t show the featured images

Hi,
I’ve tried pasting this code:

function featuredtoRSS($content) {
global $post;
if ( has_post_thumbnail( $post->ID ) ){
$content = '' . get_the_post_thumbnail( $post->ID, 'full', array( 'style' => 'float:left; margin:10px 15px px 0;' ) ) . '' . $content;
}
return $content;
}
add_filter('the_excerpt_rss', 'featuredtoRSS');
add_filter('the_content_feed', 'featuredtoRSS');

I’ve tried with a plugin too, but my RSS Feed doesn’t show the featured images when you click on it, instead, it shows an image with a sign of no picture.

I don’t know which is the origin of the problem and I’d like you to help me. I’ve also contacted the developers of my theme and tried with another one, so, the theme isn’t the problem.

The page I need help with: [log in to see the link]