“Can’t you just be amazed?” crusty scientist Frank Walker (George Clooney) shouts to young Casey Newton (Britt Robertson) about an hour into Brad Bird’s flamboyant but clumsily didactic sci-fi epic. The line represents the spirit of “Tomorrowland” in a nutshell: the movie has a hectoring tone; it constantly nudges us in the ribs, demanding that we acknowledge not only how amazing it is and how delighted we are, but how important its message is. But it’s deficient in magic and decidedly short on enchantment, as well as tiresomely preachy.

That’s disappointing in a film from the man who gave us “The Iron Giant,” “The Incredibles” and especially “Ratatouille.” But it’s perhaps understandable in view of Bird’s last effort, “Mission Impossible: Ghost Protocol,” which was an efficient enough entry in the series but demonstrated that his special directorial gifts weren’t readily transferable to live action. His return to the family-friendly genre would appear to be a labor of love; after all, he shares story and screenplay credit as well as doing helming duty. But in the event his dedication to the project seems as misguided as that of another Pixar alumnus, Andrew Stanton, whose turn to live action with “John Carter” was a notorious stumble. It makes one wonder whether “Tomorrowland” might have worked, or at least worked better, as an animated film. Certainly it doesn’t do so in its present form.

The picture begins badly—with Walker arguing with Newton in an on-camera interview about how best to tell their story. The dispute leads to a prolonged flashback in which we see him as an imaginative boy (Thomas Robinson) going to the Epcot Center at the 1964 New York World’s Fair to enter his invention—a jet pack that doesn’t quite fly—in a contest. He’s dismissed by David Nix (Hugh Laurie), a supercilious judge, but a peculiar young girl named Athena (Raffey Cassidy) gives him a small pin that eventually lands him in Tomorrowland, a futuristic city that somewhat resembles a gleaming white version of the emerald one.

Suddenly we’re whisked to the present, where Casey takes over. She’s an equally imaginative—and spunky—high school girl who’s constantly bombarded by messages that the earth is in bad shape but never told how to help deal with the global problems. (Robertson, unfortunately, looks way too old for the part—unless Casey had been held back five or six years, which would conflict with the idea that she’s whip-smart.) She’s the daughter of a worker at Florida’s Cape Canaveral, and tries to prevent the rocket-launching platform there from being torn down via what amount to vandalism. She’s caught, however, and on being released from jail finds one of those pins inserted among her belongings. It carries her off to the outskirts of Tomorrowland too—now apparently some sort of alternate reality that coexists with our own—and after several failed attempts makes her way into the place for a fascinating but short visit.

Tossed back into her humdrum life, Casey determines to get back to that futuristic paradise, making her way to a Houston shop specializing in comic and movie collectibles. There she’s accosted by its strange proprietors (Keegan-Michael Key and Kathryn Hahn) before being rescued by Athena, looking unchanged after all those years, who instructs her to seek out the reclusive Frank. She finds him, but after a big confrontation at his isolated farm involving some murderous robots, they’re off—again with Athena’s help—to Paris, where they embark on a spaceship hidden inside the Eiffel Tower that will speed them to Tomorrowland. But it turns out to be a very different place from the one Frank remembers or Casey just experienced.

The script, by Bird and Damon Lindelof, will go on to explain what’s going on, trying desperately—and unsuccessfully—to do so in a fashion that will satisfy action-adventure fans. But all the hubbub is really nothing more than the lead-up to a heavy-handed message about working to save the planet rather than simply talking about the dangers facing the environment. (It turns out that the shot in the opening Epcot sequence of Disney characters singing “It’s a Small World After All” was just a prelude to the main event.) And the recruitment process for the new “Rainbow Connection” that Bird has in mind uses more of those pins to identify the diverse group of dreamers that will join Frank and Casey in their quest to make things right, whatever that means. “Tomorrowland” turns out to carry the same injunctions to be all you can be and work for the betterment of all that the director’s previous films have borne—and the same strong whiff of nostalgia—but it all worked better when the tales were told in drawn form.

That’s true especially in the action scenes, which can’t escape the feel of real violence that live-action inevitably brings—but which, of course, is greatly diluted when animated. Bird tries to minimize the unpleasantness as best he can (and, of course, it’s usually a robot that gets mashed or dismembered), but frankly the slam-bang nature of the physical confrontations is still pretty strong. Quite honestly, the level of characterization would probably have been improved if the figures were drawn, too. Clooney is off his game here; there’s little charm in his portrayal of Walker, but perhaps that’s because most of his scenes are with Robertson, who’s been instructed to be overly brittle and aggressive, and quickly becomes irritating. More reliable work is done by Laurie, though he has little to do but smirk, and especially young Cassidy, whose carefully controlled turn shows a degree of restraint her elders might have been well advised to emulate. Key and Hahn play to the rafters, which isn’t nearly as enjoyable for the audience as they apparently think it is.

“Tomorrowland” is, of course, an opulent production, and in the hands of cinematographer Claudio Miranda (happily working in 2D) the sets and locations (including the Calatrava-designed City of Arts and Sciences in Valencia, which partially stand in for the title world) look fine. He has especially fertile ground in a couple of the creations of production designer Scott Chambliss and supervising art director Ramsey Avery—Walker’s house, jammed with Rube Goldberg-like security devices, and the Houston collectibles shop.

In fact, although Michael Giacchino’s score is entirely generic and unsubtle, the behind-the-camera contributions are generally so top-drawer that they throw the insipidity of the dialogue and action into even greater relief. “Where’s the bomb?” a character shouts in the film’s climatic confrontation. One is tempted to voice a reply: “There, on the screen.” But please, withhold comment until the lights come up.