Tyler Perry is expected to dominate the box office again this weekend with his I Can Do Bad Al by Myself . Like Perry's previous films, this one was not screened for critics, but they and other industry forecasters don't expect it to do badly at all. Several suggest it could come close to equaling Perry's biggest success, Madea Goes to Jail , which earned $41 million last February. Focus Features' 9 is expected to come in second after an early opening on Wednesday (apparently to take advantage of the 9/9/09 date). The film, which drew mostly positive reviews, is likely to earn $15-20 million, box office forecasters predict. Summit Entertainment is adding to the glut of horror films currently in theaters, with Sorority Row (also not previewed for critics), while Warner Bros. opens the supernatural thriller Whiteout starring Kate Beckinsale.