WHOOPEE! -- In the Kennedy Center Opera House through January 30.

The campaign to make the older generation of theater-goers seem like fools continues. Another vintage hit musical, "Whoopee!," is at the Kennedy Center's Opera House, only recently occupied by "Oh, Kay!" This suggests a plot to make new audiences believe that people who were crazy about musical comedy in the 1920s must have been squishy-headed and daft.

In the national interest, presumably, the Smithsonian Institution is offering contrary evidence. A "Whoopee!" record, sung by stars of the 1928 Ziegfeld producton, is in the museum shops as part of the Smithsonian American Musical Theater Series, and it suggests that the people who loved "Whoopee!" had a robust sense of humor.

We should know the quality of early comedy from the many properly revered films. But we see those performed honestly by the comedians of the time, while people who reproduce stage comedies often think funniness is not enough, and treat the material as being quaint, as well.

True zany comedy is complex: It combines cynicism with exuberance. When Eddie Canotor sings the famous "Makin' Whoopee," he says that marriage leads inevitably to disillionment, but also that it is irresistible. It's funny because it's an example of the human condition. But in Cantor's rose, Charles Repole is condescending. Instead of being trapped in humanity's paradozes, he seems frozen in a time preiod -- and from his behavior, it seems to have been a period when sex had jist been discovered, but nobody yet dreamed of its possibilities (whenever that was). A character who replies to the question, "Don't you believe in Providence?" with "Well, I spent a week there once, but I don't believe in it" should not be played as an innocent.

This sneering naivete does not ruin the whole production, the way it did "Oh, Kay!" Director Frank Corsaro's witty touches, which even get into his operas, perk things up. There are minor roles -- notably Leonard Drum's Indian chief -- and dances that are done with whole-hearted enthusiasm as well as cleverness, and these must approximate the delightfulness of the original show. The frankly fake sceney, in shades of burnt orange with big mobile toy cars and horses, are fun. But there's a great deal of simpering and mincing going on, setting the tone for most of the first act and part of the second. Strangely, the chorus drops it during the best choreography. The leads, however, do it consistently.

Repole is further handicapped by attempting an impression of Cantor, in addition to his impression of the silly people of yesterday. To get Cantor's pop eyes, he forces an apopletic look, which is particularly unfortunate because he's supposed to a hypochondriac, not a patient who could go at any minute. It was not the pop eyes that made Cantor a comedian. Beth Austin, as the heroine, squeaks baby talk, apparently on the idea that women spoke that way before the sexual revolution.

It's a shame that three clever but not famous songs that are on the record are not included in the show. But good zany comedy is certainly not in the category of art that should not be tampered with, and some wise editing was done in this production. A jolly Indian stereotype is one thing, but having the Indian hero ashamed of his blood and resolving the story by the discovery that his parents were, in fact, white, had to go. A blackface routine was sensibly dropped, but no one bothered to supply a different reason for the character's being unrecognizable to others. Technical problems with the sound system, which plagued the preview performance, seemed to have been cleared up by the opening.