I have applied structured aggregate rating to my website using Schema.org but after a couple of months the 1 to 5 rich snippets are not displaying for the given set of URLs in Google.
Here is an example URL:
To me this page should be displaying the rich snippets as I have tested it using the Google Rich snippet testing tool and it has flagged no issues.
So my question is: Is the site just not authoritative enough to display rich snippets yet (I have read that Google displays rich snippets "at discretion") or is there an error in my code that is not being picked up by the tool which is hindering the display, or something else?
UPDATE: I have updated my code according to @unor recommendation which clearly states rating only. I have introduced more fresh URL's into the Google index which already have ratings but the rich snippet is still not displaying...