Elena, there's a difference between NEVER and HAVE NEVER. We use the perfect when we refer to experience that spans someone's entire life: "He HAS NEVER tasted sushi" means that in all his life, he hasn't had it one time. However, if you served sushi at your party because you know that Igor likes it, and he left without eating any, you would say "He NEVER (even) tasted the sushi." So the form HAVE NEVER corresponds to никогда, and NEVER alone corresponds to так и не...