Because that's what's happening.
The search for people who can answer your question continues for as long as needed - until you find the answer you were looking for.
When an answer is posted by someone who was invited (byYedda or by yourself) to answer your question, their answer is marked with a yellow "invited by Yedda".
To be invited to answer other people's questions in your areas of knowledge and interest, be sure to list your favorite topics:
» My Settings › My Topics.
Of course, the more helpful your answers are, the more likely you are to be invited to future questions...
