THE WORLDS-collide pairing of Seth Rogen and Barbra Streisand pays disappointingly small dividends in the road movie "The Guilt Trip."

Rogen comes from the ensemble, raucous, improvised world of Judd Apatow, Streisand from scripted, star-driven Hollywood old school, and there is enough friction in this pairing to raise hopes of creative sparks.

It's Rogen who gives ground - way too much ground - surrendering his anything-goes comic inventiveness to a locked-down screenplay that is an exercise in predictable beats and outcomes.

Rogen plays Andrew Brewster, a chemist who's invested his entire personal fortune in his own line of all natural cleaning products. It's a miserable failure - Andrew is a poor salesman, his product is badly named.

As he nears the end of his fruitless cross-country sales expedition, he stops in New York to visit his mother Joyce (Streisand), and we see failure of another kind - a neglected relationship that's become too strained and uncomfortable.

Andrew senses this, and impulsively invites his mother to drive through the Southwest with him as he visits his last few cities (including Las Vegas, where all movies must stop, apparently).

"The Guilt Trip" takes its title from the shame that Andrew feels at keeping his over-involved Jewish mother (Streisand in a toned-down version of her Roz Focker character), at bay. He knows she means well. And we know that her ideas about how to rebrand Andrew and his cleaning products are more than well-meaning - they're exactly what the defensive Andrew needs, and will send the movie out on a happy note.

We know this because the movie makes it plainly evident - one of the problems here is that Andrew's initial tactics and methods are so misbegotten, we don't believe for a second that a fellow of his intelligence would have built a business around them.

And the shackles the script places on Rogen don't help his performance - he's low on energy, mumbles a great deal, and delivers many of his lines while staring at his shoes.

Streisand is a little more game here, even when required to engage in an episode of competitive eating at a Texas steakhouse. As they approach Vegas, we fear a karaoke contest wherein Rogen and Streisand sing "You Don't Bring Me Flowers," but the movie has at least that much restraint.