Tickets for "Harry Potter" author J.K. Rowling's sole appearance in America to promote her newest book sold out immediately - about 12 hours before they were slated to go on sale.

Rowling will appear at the 1,100-capacity Jazz at Lincoln Center on Oct. 16 for a Q&A about her latest work, "The Casual Vacancy." Tickets for the event - Rowling's only public appearance in the United States - were scheduled to go on sale at 10 a.m. Monday morning.

Instead, the tickets became available around 10 p.m. Sunday night and promptly sold out within an hour.

Though the online tickets vanished immediately, diehard fans who camped out at the theater's box office for two days were able to get tickets Monday morning, reports said.

Online commenters were furious about what appeared to be some kind of error, with many claiming they received no concrete answers when they attempted to find out exactly when the tickets were slated to go on sale.

"There was no transparency about when online ticket sales began," one commenter wrote on hypable.com. "Even for a veteran ticket buyer who expects ticket sales to begin at designated times, this really caught me off guard. Plus, the company was noncommittal when I asked them about how ticket sales would work."

Though the event at Lincoln Center will be Rowling's only public U.S. appearance, she will do several interviews with American media outlets to promote "The Casual Vacancy." The author is scheduled to appear on "Good Morning America," "The Daily Show With Jon Stewart" and "Nightline," as well as in the pages of USA Today.

Rowling's American publisher Michael Pietsch, said the new novel solidifies Rowling as "a genius, one of the great writers of all time."

"I expect the world to be ecstatic at the range of her imaginative reach," Pietsch told USA Today.

Tags: JK Rowling Books