Without explaining the reasons for their decision, executives at 20th Century Fox announced on Monday that they are pushing back the scheduled Aug. 31 opening of Mariah Carey's first starring vehicle, "Glitter," to Sept. 21. Since July 25, Carey, 31, has been at Silver Hill, an exclusive medical center in Connecticut that specializes in treating mental illness and addiction. Her representatives have said that neither alcohol nor drugs contributed to her current situation. The pop diva had "an emotional and physical breakdown," said her publicist, Cindi Berger, who told New York's Daily News that the announcement of the movie's delay did not faze Carey. "She's improving daily," Berger said Monday night. Carey has not been able to promote the movie, which is a rags-to-riches tale of a singer in the mold of "A Star is Born." Carey also serves as one of the movie's producers. Meanwhile, reports the News, other producers involved in the film are debating whether or not to delay the release of the "Glitter" soundtrack, too.