You can't use self-signed SSL certificates with Facebook. A self-signed certificate has no way for Facebook to authenticate that the site is actually who it says it is. You'll need to get a real SSL certificate issued by an SSL Authority. We have a full guide on how to do so in the article below, which can cost as little as $12/year (multi-year) or under $20 for one year:
SSL Certificates for Facebook
Hope that helps,
Alex