I have asked some questions over my tenure here that I have tried to promote with bounties. After limited success, I have started to offer smaller bounties, but still received no answers. Is there a next step for such questions?
One possible next step is to get out there and do some research and recruitment. Find relevant real-world experts and ask them to either answer here or give you pointers. Hit the library and look up as many relevant sources as you can, and follow up on their citations. Put the results of your work into an answer, even if it's partial, or into the question post, as appropriate. The more you move the ball forward, the more likely that someone else may be able to carry it further.
What should I do if no one answers my question?
First, make sure you’ve asked a good question. To get better answers, you may need to put additional effort into your question. Edit your question to provide status and progress updates. Document your own continued efforts to answer your question. This will naturally bump your question to the homepage and get more people interested in it.
Aside from that, I would consider advertising the question on fora devoted to more specific topics, such as a safrus listserv for a safrus question, while of course adhering to those fora's rules and mores.
I've had this problem with a few questions. I surmise that in my case, it may be one of two primary reasons:
1) The question is not interesting. I have to admit, that a good part of my own ego goes into the question. I think it's interesting, and I assume that readers will think it's interesting, as well. Most of the time, it is that way. But, despite that, sometimes, readers just aren't interested in the topic of the question or the question, itself.
Along with that, I find that sometimes a question that I thought was interesting at the beginning has been so overloaded with comments and discussions - sometimes "battle" (you know - the "aggressive" comments and banter that focus on one or two points that some people can't let go,) that ... well .. let's say I get tired of reading that to the point where I start to lose interest in the question itself. Maybe, you've experienced this phenomena, as well. I don't have a simple answer on this. Perhaps, you can request a moderator to remove the useless stuff, which they are usually good at doing. Despite that, though, people have memories of what happened. It's like when the jurors are told, "Ignore what was just said."
2) I've had a number of "stumpers". Sometimes I ask a questions because I just thought of the idea and if I ask my rabbi, he knows the answer. So, why do I ask my question, here, at all??? (Hmmm ... maybe you can answer that one :-) But, there are many times when my rabbi doesn't know the answer. And, sometimes he tells me, "Go ask it on Mi Yodeya!" I know that's not what this forum is for, but, reality is ... this site does seem to get Rabbinical approval. It depends whose hashagacha you want to trust.
So what should you do in these situations? For 1) re-evaluate the question. And, re-read the useful comments. I've learned much from people's comments to me. Sometimes, I vehemently disagree with a comment, and it can get "feisty", occasionally. But, if I'm really convince that I'm correct, it's sometimes still worth making the point. And, perhaps, including additional items, as I locate them. Some people, I think, delete the question or give up on it to be "politically correct". I'm not sure I understand that idea.
I don't have a great suggestion for "stumpers". Sometimes, you may have to narrow down the question. You may have included a theoretical or rare scenario that no one has encountered. And, such situations, may relay back to #1 - it makes the question uninteresting because people can't relate to that scenario. So, check if you're in that situation.
Hope some of this helps.