In "Happy Feet Two," there's precious little of what gave the original "Happy Feet" its incongruous, yet infectious charm: a tap-dancing penguin.

　　 The gotta-move protagonist of the first animated, Antarctica-set feature - a misfit young Emperor penguin named Mumble - returns for the sequel. Only this time he's all grown up . . . and a lot less fun.

　　 In his place are a lot of other polar creatures vying for screen time, and our attention. There's an elephant seal named Bryan (voiced by Richard Carter); a flock of skuas (imagine carnivorous sea gulls); a pair of bioluminescent krill shrimp trying to move up the food chain (Brad Pitt and Matt Damon); and an odd-looking marine bird named Sven (Hank Azaria), whom everyone presumes is a penguin, but who inexplicably can fly.

　　 It will be pretty obvious, to all but the 英文影评 viewers, that Sven isn't what he says he is. Neither is "Happy Feet Two," which is a largely mirthless affair.

　　 Robin Williams returns in the dual roles of penguins Ramon and Lovelace. But the joy seems to have gone out of the actor's vocal performances, which call for him to alternate between a broad - and not especially funny - caricature of a Spanish accent, and his patented Barry White schtick. Bryan, for his part, talks in a thick Australian dialect, and Sven seems to have arrived from somewhere near - but definitely not in - Scandinavia.

　　 On paper, the idea of casting Pitt and Damon as social-climbing crustaceans Will and Bill the Krill sounds goofily inspired. On celluloid, it's pointless and stupid stunt casting.

　　 It's also more than a little confusing. These side stories only serve to distract from the main narrative, which has to do with Mumble's (Elijah Wood) attempt to save his colony when it becomes stranded from its food supply after a collision of massive icebergs. That plot takes a long, long time to even kick in. And when it finally does, it's a bit of a letdown.

　　 But the biggest letdown is the absence of dancing. Mumble, the former hoofer, is now the father of a penguin chick named Erik (Ava Acres). He spends most of his time putting his foot down in other, less toe-tapping ways, after Erik, who doesn't like to dance, runs away from home, and Mumble is forced to go get him and bring him back, scolding his wayward charge the entire way.

　　 So much for happy feet. The film is permeated by a sour sense of obligation that bogs down the whole mood. Even the requisite father-son bonding that ensues feels perfunctory.

　　 Then there's the moral of the story: "If you want it, you must will it, and if you will it, it will be yours." That message gets articulated, ad nauseam, in the context of everything from Sven's improbable ability to fly, to Will and Bill's idealistic attempt to reinvent themselves as predators, to Mumble's ability to rescue his colony from starvation.

　　 It's a pretty sentiment. But "Happy Feet Two" proves precisely the opposite. Sometimes just wanting something - in this case, the pure pleasure of the first film - is not enough.