In the Sophie Kinsella book "Confessions of a Shopaholic," Rebecca Bloomwood is a wily shopaholic and excuse machine (about why she cannot pay her credit card bills).

In the big-screen comedy of the same name, Rebecca Bloomwood is a ditsy clothes horse who, looking for some champagne and a gin-and-tonic at a formal dinner, ducks into the kitchen. Where, of course, the chef promptly hands her a tray of food so she can play waitress to the guests at her table.

Although it's not unusual for a book to differ from a movie, Rebecca's redemption on film seems straight out of a "Today" show self-help segment designed for our troubled economic times. Cannot have laughs without the lessons, I guess.

Isla Fisher, the Amy Adams lookalike from "Definitely, Maybe" and "Wedding Crashers," is Rebecca, a magazine writer who stumbles into a tryout with a financial publication. It's run by the dreamy Luke Brandon, played by Hugh Dancy and here looking like a cross between a young Colin Firth and Hugh Grant.

Rebecca's financial experience consists of dodging bill collectors and calculating sale prices in her head. All of a sudden, she's expected to write knowledgeably about store card APRs, or annual percentage rates (like Rebecca, I can Google).

"Shopaholic" tracks Rebecca as she tries to keep her head above water and, in the grand tradition of "Bridget Jones's Diary" and other chick flicks, falls under the seductive sway of her boss.

Fisher may not be as wide-eyed as doppelganger Adams, but she brings a sweetness and innocence to Rebecca. However, the character becomes the toast of the international financial world in ridiculously short time, and the movie tries to milk laughs from cheap gags -- walking into a glass door or sliding down a conference table, with a meeting in progress.

Watching Joan Cusack and John Goodman play Rebecca's parents, I had a nagging suspicion that Cusack was a little on the young side for this. Turns out she's 46 (a decade younger than Goodman) and Fisher just turned 33, so you do the math.

The movie, directed by P.J. Hogan, rings truest when it deals with the siren call of shopping, but the screenplay by Tracey Jackson, Tim Firth and Kayla Alpert is especially weak when it tries to explain Rebecca's addiction.

Scenes tied to a fashion magazine play like pale imitations of "Ugly Betty" and a story strand about Rebecca's roommate seems like a time killer in an unevenly paced movie.

On the plus side, the fashions worn by Fisher are pure eye candy, designed by Patricia Field of "Sex and the City" fame. The costumer, who opened her first boutique in Greenwich Village in 1966, had a dream actress to dress.

The clothes are wickedly wonderful, but the movie too often feels off the rack.

First Published: February 13, 2009, 10:00 a.m.