The thinking behind "Meet the Parents" is obvious enough — namely, trying to repeat the success of the R-rated smash "There's Something About Mary," but doing it as a PG-13-rated film, thereby opening it up to an even bigger audience.

That sounds easy enough, though one thing the filmmakers of this only erratically funny comedy should have realized is that mining box-office gold can't possibly be as simple as bringing in the star of a hit film, which, in this case, would be "Mary's" picked-on-and-kicked-around Ben Stiller.

However, the humor here isn't nearly as "inspired" or as consistently funny as it was in the Farrelly brothers' blockbuster. "Meet the Parents" is much too herky-jerky to be completely successful, and it follows each laugh-out-loud scene with one that is completely — or is at least a bit — cringe-worthy.

However, one wise thing the filmmakers did do was find Stiller an ideal, on-screen foil, in the person of Robert De Niro, who is quietly carving out a new career for himself with a series of loopy comedy roles ("Analyze This"). The on-screen chemistry between these seemingly mismatched actors goes a long way toward making the film at least somewhat watchable.

And it's a premise that's rife with possibilities. Greg (Stiller), a male nurse, is ready to propose to his live-in girlfriend, Pam (Teri Polo). The problem is, she's a traditional girl who believes a suitor should first get the approval of her father, Jack (De Niro).

Fortunately — or perhaps, unfortunately — for Greg, he may get his chance when he and Pam head to New York for her sister's wedding. And the eager, would-be-fianc has come bearing gifts.

Nothing could have prepared him for the weekend that follows, though. Things go wrong almost immediately, when the airline loses his luggage, and only escalate with a series of misunderstandings between Greg and Pam's father, mother, relatives and longtime friends.

What's worse, Greg seems to uncover evidence that her hard-to-impress father isn't really the retired horticulturist he claims to be but instead may be a CIA agent who's got something shady going on oversees.

That sounds like pretty promising material, and admittedly, it does lead to some very funny sequences (particularly those dealing with air travel and those concerning Greg's and Jack's mutual distrust).

But director Jay Roach (the "Austin Powers" movies) and a team of screenwriters would rather take the cheap way out with a series of unfunny jokes that refer to Greg's rather unusual last name (which probably can't and shouldn't be repeated here), as well as other material that really pushes the PG-13 rating.

So it's probably fortunate that they have such a likable, funny cast. Stiller plays Greg perfectly as a frazzled bundle of nerves, while De Niro tries to steal the film out from under him — by making some of its more lackluster scenes funny with just a suspicious look. (However, usually funny Owen Wilson is largely wasted in a do-nothing role as Pam's former boyfriend.)

"Meet the Parents" is rated PG-13 for crude sexual humor and profane gags based on character names, scattered strong profanity, drugs (marijuana, seen but never smoked), simulated sex (overheard) and glimpses of nude photos. Running time: 108 minutes.