Are we not counting Haiti or Jamaica? If we’re counting “black” as “African”, then yeah. But then “There are no successful African countries” seems a lot less difficult to prove/refute.
Jamaica, and especially Haiti, are in no way "successes". The Dominican Republic is not exactly a rich country, but the contrast between it and Haiti are so stark as to beggar the imagination.
Relevant: TIL that Haiti has had 23 constitutions since 1801, with the most recent being enacted in 2012. At least two have declared the country to be an empire. <https://np.reddit.com/r/todayilearned/comments/3t5wzt/til_th...>