Am trying to give a bounty in this question Limiting internet bandwidth for already started applications but somehow the option does not appeared. I tested on Firefox 4 and Chrome 12/13. It appears in other posts but not that one.
A question must be older than 2 days before you can add a bounty.
For completeness' sake, you also can't add a bounty to a question that has an accepted answer.
See also: http://meta.stackoverflow.com/content/stackoverflowmeta/img/favicon.ico How does the bounty system work?
i doubt that you can't add a bounty to a question that has an accepted answer.– LincityJun 8, 2011 at 6:16