(Rated PG-13, 95 mins.) Not to be confused with “The Black Knight” starring Alan Ladd in 1954 (yeah, sure), Martin Lawrence stars as Jamal Walker, a fast-talking con man stuck in a job at a medieval theme park. One day he finds himself slipping through the park’s moat and into a world of 14th century England where he teams with an ex-knight, Sir Knolte (Tom Wilkinson) and a beautiful peasant girl (Marsha Thomason) to defeat the evil king. Directed by “10 Thing I Hate About You” Gil Junger, it’s a riff on Mark Twain’s “A Connecticut Yankee In King Arthur’s Court.” Not just another stupid comedy, Lawrence is amusing, attempting to carry the lead load, but it’s watching Wilkinson, a trained British actor trading in that for this that is entertaining.