When he tells you no sometimes it means no, not right now. Just because he says not right now, doesn't mean he won't say yes at a later date.
When the Lord said if there was any other way and the cup could be passed from him, then let it be done, but if it be the father's will, so be it. The father did indeed answer the prayer, because shortly afterward he stood up and walked to his destiny.
On the other hand, sometimes him not answering is his way of building up our patience and endurance to serve him.
Luk 11:5 And he said unto them, Which of you shall have a friend, and shall go unto him at midnight, and say unto him, Friend, lend me three loaves;
Luk 11:6 For a friend of mine in his journey is come to me, and I have nothing to set before him?
Luk 11:7 And he from within shall answer and say, Trouble me not: the door is now shut, and my children are with me in bed; I cannot rise and give thee.
Luk 11:8 I say unto you, Though he will not rise and give him, because he is his friend, yet because of his importunity he will rise and give him as many as he needeth.
Luk 11:9 And I say unto you, Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you.
Luk 11:10 For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened.
Luk 11:11 If a son shall ask bread of any of you that is a father, will he give him a stone? or if he ask a fish, will he for a fish give him a serpent?
Luk 11:12 Or if he shall ask an egg, will he offer him a scorpion?
Luk 11:13 If ye then, being evil, know how to give good gifts unto your children: how much more shall your heavenly Father give the Holy Spirit to them that ask him?
Or also stated in Matthew...
Mat 7:11 If ye then, being evil, know how to give good gifts unto your children, how much more shall your Father which is in heaven give good things to them that ask him?
Be patient and steadfast in prayer, and if God finally says, you know what? I've already said no and stop asking, then it's time to stop asking. But I've hardly ever heard anyone be that diligent in prayer and have God finally say no for the last time.