Singin' in the Rain, Sadler's Wells, London

Of all the post-war MGM musicals, Singin' in the Rain is the greatest - but for non-musical reasons. It's a satire on 1920s Hollywood, made by people who obviously spent their younger days gazing in wonder at the silver screen. Putting it on stage loses the lovely self-mockery of a movie about movies.

This new stage version, a co-production by Sadler's Wells and the Leicester Haymarket, loses more than that. It keeps the film's songs, and its witty script by Betty Comden and Adolph Green. But it's a stiff and plodding transfer.

The star is the ex-Royal Ballet dancer Adam Cooper, who plays the film star Don Lockwood, Gene Kelly's role in the original film. He also choreographed the dances. They don't reproduce the movie's numbers, though there are some overlaps: some tap, some ballet steps, some all-purpose chorus dancing. But Cooper doesn't know how to build a number, how to give short sequences cumulative force. His chorus work hard, and show touches of style, but they never let rip.

Cooper's own dancing provides the evening's happiest moments. He's more relaxed than anyone else on stage, and there's an open ease to his jumps and slides. Splashing through the title number, he looks gleefully happy. Ronni Ancona, however, famous for her impressions, looks adrift in an acting role. As Lina Lamont, Jean Hagen gave the movie's funniest performance, with a voice like a squeaking hinge. Ancona screeches with a will, but she doesn't show us Lina's monstrous self-confidence, or her real starriness.

Josefina Gabrielle plays Kathy Selden, the actress hired to dub Lina's voice. It's an ingenue role, but hers is hardly an ingenue voice. She's a belter, with a grainy vibrato. Simon Coulthard, as Don's best friend Cosmo, is hyperactive but never spontaneous.

It's not just Coulthard. Under Paul Kerryson's direction, voices are miked throughout, but you can still hear the actors pushing up the volume, as if they don't believe they'll be heard over the band. The music, under Julian Kelly's direction, has some vigour, but the playing is loud rather than jazzy.

Then there are the creaks of the staging itself. Robert Innes-Hopkins has designed a flexible set - a sunset sky with doors that fold back for a soundstage, a row of Hollywood Egyptian pillars for a studio office. But the changes take far too long. In one, as Don and Kathy walk slowly across a lowered gantry, covering the scene change behind them, we can see drips of the rain ready for the title song.

To 4 September (0870 737 7737)