Everything about ?Because I Said So? screams out generic chick flick ? and we do mean scream, literally ? from the forgettable title to the excruciatingly corny ending.

In between, director Michael Lehmann runs through a veritable checklist of cliches. (Is it possible this is the same man who made the deliciously vicious ?Heathers? nearly 20 years ago?)

There are the unbelievable characters who say and do contrived, sitcommy things. The montages of shopping and furniture rearranging. The caffeinated score to punctuate all those wacky moments (Diane Keaton discovering online porn). The gaggle of women discussing their sexual hijinks with ?Sex and the City?-style bluntness. And of course, the repeated cutaways to a cute dog reacting to all this shrill nonsense.

If there?s a cake ? and there are several, with Keaton and co-star Mandy Moore both playing caterers ? you know it won?t be long before someone?s face gets smushed into it. The gag isn?t all that funny the first time. That?s the kind of movie this is.

Keaton stars as Daphne Wilder. (An homage to Billy? Let?s hope not.) She?s an overly meddlesome, highly emotional mother of three grown daughters who worries that her youngest, Milly, will stay single the rest of her life.

Which is silly, because she looks and sounds just like Mandy Moore. But such is the premise in the script from Karen Leigh Hopkins and Jessie Nelson (?Stepmom?), who write women as if they?d never even met one.

Daphne?s other two daughters (Lauren Graham and Piper Perabo) are married off at the film?s start, with Milly functioning as the perpetual bridesmaid ? a role she doesn?t seem to mind, but one that sends her mother into hysterics.

So naturally, Daphne does what any mother would do: She crafts an Internet ad for Milly and secretly arranges the girl?s dates. (This leads to yet another staple of the genre, the bad-first-date montage.)

Of all the men she meets in a chic hotel lobby bar, two would-be suitors emerge who are so vastly opposite, it?s obvious whom we?re meant to root for from the start.

Jason (Tom Everett Scott) is a workaholic architect who likes red wine, dresses beautifully, drives a flashy sports car and speaks Italian. As if we couldn?t determine that he?s Mr. Wrong from all that, he also lives in a cool, modern home high in the hills, the style of choice for all heartless film figures.

Johnny (Gabriel Macht), meanwhile, is a musician who happens to be playing in the bar during Daphne?s date-o-rama, and becomes intrigued about her daughter. He?s easygoing, wears vests and has tattoos, and drives a beat-up, vintage ride. He also lives in a cozy little cottage along the canals in Venice, California.

Say no more!

Milly ends up meeting and dating them both ? though she remains clueless that her mother knows both of these people, because Daphne is lying to her under the guise of love.

The other sisters get involved, offering unsolicited advice, until ultimately all these women are screaming at each other or crying, or both. (In one scene, they also get screamed at by overzealous Korean masseuses in an especially distasteful stereotype.) And sometimes they break into song at parties, which can be even more painful to watch.

Moore is far too lovely and talented for this ? she?s proven in movies like ?Saved!? and ?American Dreamz? that she has great timing and presence and possesses far more depth and bite than her pop-star history might suggest.

And Keaton? Here she?s reduced to a cartoon character, and by now she should know better. Then again, after ?Hanging Up,? ?Town & Country? and ?The Family Stone? over the past few years, maybe not.

The only moment that feels vaguely real in the entire movie comes when Moore is asked to describe what an orgasm is like. She does so quite accurately and convincingly and without making you want to cringe.

It?s the one time in the film that no one is faking it.

?Because I Said So,? a Universal Pictures release, is rated PG-13 for sexual content including dialogue, some mature thematic material and partial nudity. Running time: 111 minutes. One star out of four.