Actresses Blake Lively and America Ferrera (R), stars of the film 'The Sisterhood of the Traveling Pants 2', pose during a portrait session in New York in this July 27, 2008 file photo. [Agencies]

By Hollywood profit standards, the cast and producers of the sequel to "The Sisterhood of the Traveling Pants" admit they were surprised another film based on the hit book series was even made.

The sequel is released in the United States on Wednesday even though the original 2005 film made only $39 million in North America and $2.9 million overseas.

But with a loyal audience generated by fans of the best-selling young adult book series, guaranteed DVD sales and rising careers of some of the four main female actors, makers of the sequel are hoping that translates to greater success.

"By Hollywood standards maybe one would say that the first one wasn't as successful as other films, in truth," the film's producer Kira Davis told reporters recently. "If you go by the actual business side of things I think nine times out of 10 there wouldn't have been a sequel from that movie."

The series about the power of friendship tells the story of four girls who acquire a pair of magical jeans. The sequel -- which is made by Time Warner Inc's Warner Bros and squeezes the last three of the four books into one film -- follows the girls after their first year of college.

The biggest actor in the current film, Emmy award-winning America Ferrera, 23, who plays the title character in the popular U.S. television series "Ugly Betty," told Reuters she too was surprised by the sequel.

"While it had a nice core audience, it wasn't a huge success at the box office so I was a little surprised when we came back to do the second one," she said, pointing to the established book fans and DVD audience as a possible reason it was made.

Ferrera and co-star Blake Lively, 20, who stars in the new controversial U.S. teen TV series "Gossip Girl," were relative unknowns when the first film was released, but now both have blossoming careers.

Ferrera hopes the audiences for their television shows would likely want to see the new film.

Davis noted the original had strong DVD sales. The original film's DVD was available the same day at Chinese retail outlets to take advantage of sales before pirated copies were made.

"My fellow producers and the following of the movie really felt like these characters had to live on, on the screen. We felt like we couldn't let it stop," she said.