It is vitally important to recognize that the Lord also responds a third way to prayer by withholding an answer when the prayer is offered. Why would He do that?
He is our perfect Father. He loves us beyond our capacity to understand. He knows what is best for us. He sees the end from the beginning. He wants us to act to gain needed experience:
When He answers yes, it is to give us confidence.
When He answers no, it is to prevent error.
When He withholds an answer, it is to have us grow through faith in Him, obedience to His commandments, and a willingness to act on truth. We are expected to assume accountability by acting on a decision that is consistent with His teachings without prior confirmation. We are not to sit passively waiting or to murmur because the Lord has not spoken. We are to act.
-- Elder Richard G. Scott, “Learning to Recognize Answers to Prayer,” Ensign, Nov 1989, 30 (emphasis added)