It rather depends on the question:
If it's a finite problem (as yours seems to be) I would personally only accept answers that solve the problem. A suspicion can fit into that category if it proves correct and helps you solve the issue.
If there is more than one possible answer (and you have some to choose from), pick what you find the best. You don't have to do it immediately and you can change your pick later on.
The meaning essentially comes down to which post the opening poster thinks is best. It's the answer you pick. It rewards the poster with 15 reputation points (assuming it's not a community wiki) and pushes the answer to the top of the stack (usually), making it more likely to attract further votes.
It's also a strong indication to people that visit the site (with the same problem as you) that this is the post they should be reading. It's your responsibility as OP not to mislead them. But ultimately it's your call. Other users can only vote on the answers. We can't overturn an acceptance.
If you're worried about a low accept rate, go through your old open questions. If you can accept something in good faith, accept it. If you can still work with an answerer (eg it's a problem you have still) give them a poke.
If you can't resolve the question positively I would personally rather you left it open (and perhaps stuck a bounty on it) or deleted it, than accept an answer which does not help, or worse, is not helpful at all.
It's almost 4am and I'm running on five hours sleep from last night so I doubt this post makes any more than 75% sense. I'll give it a read through tomorrow and follow up.