Green Lantern may have a future on the big screen, but likely not with the same director. Despite the big-budget superhero movie’s disappointing box office performance so far, Warner Bros. executives still want to find a way to make a sequel work. Bringing superheroes from its DC Comics unit to the big screen is a top priority for the studio, and executives believe that the problem with “ Green Lantern ” was in execution, not concept. They even have ideas on how to turn things around next time. “We had a decent opening so we learned there is an audience,” said Warner Bros. film group President Jeff Robinov, pointing to the film’s box office debut of $53 million. “To go forward we need to make it a little edgier and darker with more emphasis on action…. And we have to find a way to balance the time the movie spends in space versus on Earth.” After its so-so opening, “Green Lantern” fizzled at the domestic box office, ending up with only $114 million. Its overseas performance in i