When Bertelsmann Direct Group,the music and book direct-marketing arm of German media conglomerate Bertelsmann AG,launched its business in China in 1995,it seemed like a winning idea.The company's book clubs,a catalog mail-order operation offering cut-price books in return for a monthly membership fee,had proven a hugely lucrative business in Europe;and China,with its huge,highly literate population,seemed an ideal market for expansion.