The key to Cox's appeal on R&B radio and in gay discos is her melodramatic flair. On her third album, she infuses the best tunes with a fun combo of camp and conviction. The boo-hoo ballad ''Hurts So Much'' finds her groveling for love. And the dance-floor burner ''Mr. Lonely'' puts her in ''I Will Survive'' mode. But too often the bloodless sentiments fail her. She's a scenery-chewing actress without enough meaty roles.