SINCE making her debut as plucky high school misfit Lizzie McGuire on TV in January 2001, life has been one long fairy-tale for Hilary Duff.

Her subsequent film projects - Agent Cody Banks, The Lizzie McGuire Movie and Cheaper By The Dozen - have all been modest hits and her solo debut album, Metamophosis, went to number one in the US charts and has since gone triple platinum.

However, even fairy-tale princesses have their off days.

A Cinderella Story, a modern day spin on the classic romantic yarn, is the effervescent 17-year-old's first, ahem, duff film project.

In the aftermath of an earthquake which kills her father, Samantha Montgomery (Duff) moves into the attic of her San Fernando Valley home to make way for her cosmetically enhanced stepmother Fiona (Jennifer Coolidge) and two image-obsessed stepsisters Gabriella (Andrea Avery) and Brianna (Madeline Zima).

Sam pays her way by ensuring she is at Fiona's beck and call, and by working every hour under the sun in her stepmother's trashy 50s diner, run by the sweet and generous Rhonda (Regina King).

Against her better instincts, Sam goes to her high school prom in disguise, where she learns that a secret web-chat admirer is hunky quarterback Austin Ames (Chad Michel Murray).

The teenagers spend a magical night together but Sam is forced to leave early to ensure she is back at the diner for an inspection by her stepmother. In her haste, Sam drops her mobile phone and Austin sets out to track down his mystery date.

A Cinderella Story has a major identity crisis, torn between over-the-top comedy and cloying teen angst.

The two moods stubbornly refuse to gel and the screenplay and performances slowly but surely tear the film apart.

On one side, Coolidge totters and pouts for all she is worth as the collagen-heavy pantomime villainess; on the other, Duff sobs and wails, trying to elicit our sympathy for her poor, put-upon orphan.

Very occasionally, the humorous banter between the evil stepmother and her scheming daughters threatens to spark the film to life.

If A Cinderella Story had been played entirely for laughs, Duff may just have continued her winning streak.

The plot abandons the framework of the Cinderella fairy-tale to suit its own sentimental ends (the mobile phone, oddly, serves no dramatic purpose, unlike the glass slipper), building to a bouncy, feel-good resolution that left me feeling a little nauseous.

Duff seems to be missing her usual vivacity and bubbliness and she doesn't kindle a great deal of screen chemistry with Murray, who looks far too old to be in high school.

King's fairy godmother figure is a clumsy plot device rather than a fully formed, three-dimensional character. She deserves far better - so do we.

See it at UCI, Odeon