The original ad works because the image is generated from server side, and the server uses Stack Exchange API to know the number of active bounties.
Current Ask Different bounties http://stack-exchange-dynamic-ads.herokuapp.com/apple.stackexchange.com/bounty.png
The correct one for us is the following one. I am on my iPad mini, so it's a little hard to write this answer.
Current Drupal Answers bounties http://stack-exchange-dynamic-ads.herokuapp.com/drupal.stackexchange.com/bounty.png
In the case you need to use it for other Stack Exchange sites, this is the Markdown markup to create it. Replace
<stack-exchange-id> with the Stack Exchange identifier for the site (the subdomain currently used for the site you are interested).