Welcome to the forum.
You have already been told to start every sentence with a capital letter so there's no need to repeat that. I find your sentence a little unnatural. I would expect to hear either "He keeps his promises" when talking about a habitual action or "He kept/will keep his promise" when talking about one specific promise. The present tense doesn't really work with the singular.
If you are going to use "correct", then use "incorrect" as the opposite. If you want to use "wrong", then use "right". It's unnatural to put "correct" and "wrong" together, or to put "right" and incorrect" together.