Horror is a tricky genre, especially in cinema. Some films terrify the audience, while others fail in scaring the viewers, instead making them laugh. Some directors drift into the genre from time to time, while others build their careers on providing the cinema goers with a certain level of thrills.
It seems obvious that directors who are not specialists in the genre may fail in their attempts to scare the genre aficionados. Directors who made their name making horror movies manage to provide the viewers with quality fright. But, sometimes, even masters of horror can fail with their flicks. There can be many reasons behind that. Sometimes directors are just exhausted. Sometimes the misfire can be blamed on the interference of studio executives. Regardless of that, being a master of horror doesn't guarantee that your next feature won't turn out to be a misfire.