facebook comments unreachable error

The Open Graph debugger says:

Open Graph Warnings That Should Be Fixed
Inferred Property The property “og: url” must be provided explicitly, even if a value can be inferred from other tags.
Inferred Property The property “og:title” must be provided explicitly, even if a value can be inferred from other tags.
Inferred Property The property “og:description” must be provided explicitly, even if a value can be inferred from other tags.
Inferred Property The property “og:image” must be provided explicitly, even if a value can be inferred from other tags.

It seems to be fixed installing an open graph plugin!

Now, I have another question: If I a share a post in Facebook and anybody comments in, thats comments don′t appear in the website′s comments envolved as if I do on the contrary (Posting the coment in Coments Envolved results to share the post with the coment, but not the contrary). I noticed that sharing a post on google + makes it is reflected directly as a comment in Comments Envolved. I don′t know if this is an exclusive feature of Google plus or there is any issue in Facebook Comments.