Director Baz Luhrmann has acknowledged that trying to market his $50-million musical Moulin Rouge, which opens Friday, has represented "the biggest headache" of his film career. In an interview with Thursday's New York Post, Luhrmann noted that the movie, in which modern pop music is performed against the backdrop of 19th-century France, does not lend itself to poster ads. "Anyone you meet will say it's not like anything they've seen before," Luhrmann told the Post. "That comment is a good thing for the film, but it's the worst possible tag line for the marketing system." Moreover, the film itself, which opened the Cannes Film Festival last week, has attracted wildly divergent reactions. "What makes me feel that we're not in trouble," Luhrmann told the newspaper, "is that those that are positive are so extreme and so passionate."