As LD1 said, it's a matter of the OP coming back and saying/expressing/admitting what the solution to the initial problem was.
I remember having a fault that Members advised that it was a biological infestation of my fuel tank, giving advice to ascertain the fault. I adamantly said that it couldn't be that... then found that it was. I admitted it and described all of the steps on how I corrected the situation.
I did this, not to apologise, but to help future people/Members who may see the thread that I started. It's no 'skin off my nose' if I look like a twit for initially ignoring/rejecting the freely given advice that was provided. I felt morally obligated to vindicate the advice that was correctly given.
Since then, there has been numerous times that questions have been asked on TBN with no solution to their dilemma provided, despite advice given. Unfortunately, there is no obligation on the recipient to reply.
Mind you, I know that I have a thread on an inoperable 3rd function, that I have yet to solve. When it's fixed, I'll 'post'.