Why did the "successes" of the Age of Jackson begin to fail after he left office with his successors, Van Buren and Tyler?

Because successors did not have the same egalitarian and democratic goals as Jackson.

Explanation:

Andrew Jackson developed policies that would help the most undervalued population and reduce American elitism, especially in relation to large banks and corporations. Jackson tried to extend voting rights, ending electoral college and allowing the American population to be the only one responsible for choosing their representatives, promoting programs that help farmers, promoting the rotation of public offices, preventing political elitism, preventing monopoly banking, among other very populist and democratic policies that would give more freedom and progress to American society. However, his successors did not follow these same objectives, mainly because of the political and economic pressure that the big corporations and big political names imposed, which caused the successes of the Jackson era to begin to fail.

answer; taking up arms to defend the nation;