The simpler media website CMS
1.5 Implements a number of Facebook meta tags via html_meta_tags.php, including app_id. However the meta tag that results is of the form:
meta property="fb:app_id" content="1.234567890123E+14"
and the FB debugger understandably complains that this is not a valid app id. Removing "sanitize_numeric" from line 412 of html_meta_tags.php fixes the problem.