With its affectionate and shrewd lampooning of its subject, The Brady Bunch Movie represented the high-water mark of the absurd, creatively bankrupt old-TV-show-as-movie phenomenon; in fact, it rendered the genre obsolete. Try telling that to Universal Pictures, which chose to play it straight in its adaptation of the profoundly uncinematic Leave It To Beaver property. The results are about what you'd expect: The blandness and weak slapstick of the script make the low-key witticisms of the TV show sound like Wildean epigrams, and the brief cameos by a handful of the original cast members are as inevitable as they are depressing. The energy level is nil, and it's obvious no one particularly cares about what they're doing. (As the Beaver, underfed child actor Cameron Finley recreates the squinty-eyed underplaying of Jerry Mathers, but without the charisma, if that's possible.) It's difficult to understand at whom the movie was aimed: Aside from the revival of a few characters, there's scarcely any familiar Beaver atmosphere for baby boomers to glom on to, and kids probably couldn't care less about a 40-year-old sitcom. Despite all this, there's little sign the phenomenon will let up. Coming to theaters in April: Lost In Space.