This seems a direct translation from English to me. As "-chafu" is an adjective, i believe it is "dirisha chafu", like you say "hewa safi" instead of "hewa ni safi". N.B. Even when the use of "ni" is grammaticaly correct, i found that often "ni" is omitted, like people say "mimi Mtanzania" rather than "mimi ni Mtanzania".

Why "lina" instead to "ni"?