Problem with RSS thumbnail code

I have tried the different codes there are out there to include a thumbnail in the RSS feed and they do insert the thumbnail in the feed but when I view a post with a thumbnail attached to it on my website, the post excerpt is showing up on the top of the page before the wrapper.
Does anyone know why this is?
Thanks
Erik

// THIS INCLUDES THE THUMBNAIL IN OUR RSS FEED
add_filter( ‘the_excerpt_rss’, ‘voodoo_insertThumbnailRSS’ );
add_filter( ‘the_content_feed’, ‘voodoo_insertThumbnailRSS’ );
function voodoo_insertThumbnailRSS( $content ) {

global $post;

if ( has_post_thumbnail( $post->ID ) )
$content = ” . get_the_post_thumbnail( $post->ID ) . ” . $content;

return $content;
}