@Prady -- the community has been going for some years now and the folks who contribute with quality answers get consistently upvoted by others and their answers tend to get consistently marked as the solution while getting upvotes over time. You, yourself, have a fair number of reputation points.
Over time, it all just works. Take sfdcfox or Keith C by way of example. They clearly know their stuff and never solicit for having their answers marked as the solution. And because, as the top contributors, they don't solicit, the tone of the Community seems more relaxed and friendly. It's subtle, I know.
We're here to help others.
If I contrast SFSE to other SFDC forums, one often sees importuning that comes across as "hey, it's a dog-eat-dog world out there and I demand to be recognized as Mr. SFDC, so mark this as the answer...NOW!" I'm sure that wasn't your intent but this can get to be a slippery slope.
So, I tend to gently suggest not to request such recognition so the community maintains its distinctive voice as contrasted to other forums. Sebastian's answer is a good one -- if the OP engages in a dialog with you and indicates it all works now (or your answer leads to the solution), it is acceptable to say, "great, happy to help. Please mark the answer as the solution so others can benefit".
And, if the OP doesn't respond with an upvote or solution, there could be lots of reasons
- Time of day / timezones
- The OP realized they posed the wrong question and your answer isn't relevant
- The OP solved their own problem and moved on
- The OP found a better answer elsewhere and moved on
- The OP is simply churlish and ungrateful