man i think you must have not passed the minimum criteria for the 20 posts, 15 replies, and 15 responses. may be one of them might be missing ? if you feel that you have passed the criteria, then you should contact the admins, cause there are not 100 people in the forums :P so even if you were last (which you are NOT) you would still deserve some points for the forums
i think you need to email the admin and ask them your records ;)