The Google crawler does not render the snippet when the +1 button is rendered but rather when a user clicks the +1 button (or share button). What you should try is to determine what your server is sending to the Googlebot during this user initiated and asynchronous load by the Google crawler.
You can emulate this by using the following cURL command:
curl -A "Mozilla/5.0 (Windows NT 6.1; rv:6.0) Gecko/20110814 Firefox/6.0 Google (+https://developers.google.com/+/web/snippet/)" http://myurl.com/path/to/page
You can output that command to a file by adding -o testoutput.html
to the command.
This will give you an idea of what the Google crawler sees when it encounters your page. The structured data testing tool can also give you hints.
What you'll likely see is that unless your doing your snippet preparation in a static file or on the server side is that you're likely not going to get the snippet that you desire.
If you can provide real URLs to test, I can probably provide more specific feedback.