SFC ver. 0.21
NextGen Gallery ver 1.6.1
"Like and Share" button manually.
With "SFC like" and "SFC share" disabled the NextGen Album shows good
but enabling "SFC Like Button" or "Share Button" the gallery is showed in page header
with this HTML Code
where you can see body and head code mixed.
I don't know where is the problem (probably in nextgen code) but I solved changing these line, in function sfc_share_meta in sfc-share.php and sfc-like.php,
$content = apply_filters('the_content', $content);
$content = sfc_share_button_automatic($content);
I will be very happy if someone can solve finally this problem