I don't know if I know the answer to that. Perhaps God wants to teach us patience. Or perhaps He needs to work changes in the lives of others before He can give us the thing we're asking for. One thing I do know is that sometimes it is necessary to persevere in prayer.
George Muller will be remembered for his life of faith and for the orphanages he built around Bristol. He was a man of prayer. He saw thousands of prayers answered. Many of the answers came on the same day he prayed - but not all of them so quickly.
"All the children of God," said Muller, "when once satisfied that anything which they bring before God in prayer is according to His will, ought to continue in believing, expecting, persevering prayer until the blessing is granted. . . When once I am persuaded that a thing is right, I go on praying for it until the end comes. I never give up.
"The great point is never to give up until the answer comes. . . The great fault of the children of God is they do not continue in prayer; they do not go on praying; they do not persevere. If they desire anything for God's glory, they should pray until they get it."
He practised what he preached. "I have been praying for 63 years and eight months for one man's conversion," he said. "He is not saved yet, but he will be. How can it be otherwise? . . I am praying."
Muller never saw the man converted. He died first. After Muller's death, the man came to Christ.