From TV Guide Online:
MJ Is MIA:
Both Michael Jackson and his attorney were no-shows Wednesday at a hearing for the civil case which posits that the embattled pop star sexually assaulted an 18-year-old boy during the 1984 World's Fair. A rep for Jackson, who at a rescheduled Aug. 17 hearing may also face contempt-of-court charges, could not account for his client's absence, but adamantly denied reports that the singer stayed at home to finish Half-Blood Prince.
I honestly wouldn't be surprised if that were the real reason.