Leave it to director Nora Ephron to declaw a black comedy like "Lucky Numbers," turning it into something docile and almost sweet.

Writer and sometimes director of ubiquitous, twinkly Meg Ryan romances in the '90s ("When Harry Met Sally," "Sleepless In Seattle," "You've Got Mail"), Ephron just doesn't quite have the incisive sense of humor for this movie about a bankrupt TV weatherman whose Muprhy's Law life leads him to rig the state lottery. But goodness knows she makes a valiant effort.

John Travolta stars in "Numbers" as Russ Richards, the smarmy-charmy meteorologist for a Harrisburg, Penn. television station who milks his semi-celeb status for everything its worth (he has his own table and reserved parking at Denny's).

Russ Richards is a man who lives beyond his means, buying trophy homes and Jaguars on a condo-and-Volvo salary. His on-the-side snowmobile dealership is tanking because of an unseasonably warm winter (oh, the irony). And he's just been served with a foreclosure notice. Russ Richards is a man who needs money -- lots of money -- and fast.

With the help of his sniping sometimes-girlfriend Crystal (Lisa Kudrow) and an underworld pal (Tim Roth), a plan is concocted to fix the lottery and score a $6.4 million jackpot. They actually pull it off -- in large part because Crystal is the Sears-gowned hostess of the Lottery drawing, which takes place each week at Russ's TV station. But it isn't long before unanticipated blunders begin to snowball.

Unfortunately, Ephron (who also directed Travolta in "Michael") guns the engine a lot without putting "Lucky Numbers" in gear. There are several hardy chuckles, but the comedy never truly takes off because the director is busy padding the movie with falsely chipper throwaway scenes set to sing-along rock ditties and other such distractions. It's only the cast's grinning relish at playing these sharply drawn caricatures (they're not drawn sharply enough to be called characters, I'm afraid) that keeps the picture ticking over.

There's something desperate and sad about the plastic personality of Russ Richards that Travolta really taps into, then gives it a deft comical twist. Sometimes the guy seems on the verge of crying he feels so sorry for himself. Russ isn't nearly as bright as he thinks he is, and he honestly can't understand why things aren't magically going his way.

He plays well off Kudrow's terrifically tart performance as the shallow, quarrelsome Crystal, who considers herself the brains of the operation and isn't above a little sex or a little murder to keep the plan on track.

Clumsy criminals that they are, Russ and Crystal attract a queue of equally bumbling blackmailers. A suspicious station manager (Ed O'Neill) catches them in the act and demands half the money. The chump they recruit to collect on the ticket (derisive documentary-maker Michael Moore) decides he wants a bigger cut. Dale the Thug (Michael Rapaport), who wields a baseball bat for a living, wants $500,000 -- or else. And Roth, of course, wants 20 percent for helping cook up the plan in the first place.

Then there's Bill Pullman, featured in an afterthought of a subplot as a lazy, inept cop who almost stumbles onto the scheme.

But while all these actors contribute to the movie's humor, their characters don't help the story's cohesiveness. Ephron just never finds a consistent rhythm or energy level.

Then there's that awkward ending. "Lucky Numbers" is based on a true story, but it fudges the finale -- big time. Were there reshoots because a test audience somewhere didn't feel upbeat enough afterwards? I wouldn't be a bit surprised.