It's not allowed under the current system. See Bounty-like facility for rewarding excellent questions and any of its duplicates for the rationale.
The problem with offering bounties on questions is it doesn't encourage any behavior from other users. When users see a bounty available on a question, it encourages them to provide a detailed answer in an ...
That's the risk you take with a bounty. Once the bounty is set you lose the points.
No one is under any obligation to answer your question and if no one knows the answer then they're not going to answer bounty or not.
I can only suggest that you add any extra information you've managed to find from your continued investigations - you are still actively ...
There is a blog post which describes in depth how the bounty system works. In essence, the answer to your question is that
all bounties are completely independent of and unrelated to accepting an answer.
The idea is to get people to have another look at a question if it hasn't had enough attention. Even if the original poster accepted an answer as "good ...
Although the grace time is up, the scripts which allocate the bounty hasn't seem to have run yet.. give it another few hours, it should allocate the bounty. Else we'll move this as a bug report.
It's worth pointing out that Bounty allocation and answer acceptance are two separate events and one need not necessarily cause the other to trigger.
Nice to see your question answered. I would say (in this particular case...):
Cut Asymptotically some slack and give him his 50 rep. back (upvote question on WebApp)!!
Here is the Q&A : Google Calendar colorize weekends in Firefox