Although it was a somewhat childish determination because Dhruva Maharaja was nothing but a small child, Lord Visnu, the Supreme Personality of Godhead, is so kind and merciful that He fulfilled Dhruva's desire
SB Canto 4
Despite having achieved the desired result of his determination by worshiping the lotus feet of the Lord, Dhruva Mahārāja was not very pleased. Thus he returned to his home.
By worshiping the lotus feet of the Lord in devotional service as instructed by Nārada Muni, Dhruva Mahārāja achieved the desired result. His desire was to get a very exalted position, excelling that of his father, grandfather and great-grandfather, and although it was a somewhat childish determination because Dhruva Mahārāja was nothing but a small child, Lord Viṣṇu, the Supreme Personality of Godhead, is so kind and merciful that He fulfilled Dhruva's desire. Dhruva Mahārāja wanted a residence more exalted than any ever occupied by anyone else in his family. Therefore he was offered the planet in which the Lord personally resides, and his determination was completely satisfied. Still, when Dhruva Mahārāja returned home he was not very much pleased, for although in pure devotional service there is no demand from the Lord, because of his childish nature he had demanded something. Thus although the Lord also fulfilled his desire, he was not very pleased. Rather, he was ashamed that he had demanded something from the Lord, for he should not have done this.