Aaayy! There's a reason sitcom was half an hour

If you called the phone number listed for the Broadway Series at the Academy of Music on Tuesday night, when it opened the stunningly lame new musical called

Happy Days

, you got a taped message that the box office would be back in business sometime after New Year's.

Is anybody minding the store over there? Apparently not, or someone would have changed the message by now - and also would have nixed the possibility of booking Happy Days, which runs through the weekend and appears to be a stage collaboration by Lackluster and Uninspired.

How Happy Days got into the heavily marketed Broadway Series - it was never on Broadway and I suspect it wouldn't last a week - probably involves some arcane way in which the series draws from available national tours. How it got producers' backing is not so puzzling: The creative team for Happy Days has stars, rarely so unaligned.

The book for the show is by Garry Marshall, the super-smart writer who gave us the TV sitcom for which the musical is named, plus Laverne & Shirley and Mork & Mindy, and whose film-direction credits include Runaway Bride, both Princess Diaries, Pretty Woman, and Beaches. Composer Paul Williams, who wrote "I Won't Last a Day Without You," "Rainy Days and Mondays," "Evergreen," and other songs that are now standards, did Happy Days' music and lyrics.

Their work makes a wholly unintended point about musicals set in the late '50s, when doo-wop was turning to cool bop: First there was Grease, and then there was - Grease.

Grease worked fine as a movie and, with clever theatricality, on the stage. Happy Days worked fine in half-hour sitcom segments. It lasted 11 seasons, topped the mid-'70s TV charts, and, in this stage version, holds about the standard sitcom-length 30 minutes of good stuff in its two-hour-and-20-minute elongation.

A built-in problem: Happy Days' main man, the Fonz - the cooler-than-Carrier character whom actor Henry Winkler inhabited (and who, in a way, inhabited Winkler's career) - is tough to replicate as anything more than an impersonation.

Actor Joey Sorge (The Drowsy Chaperone) does a game job of it, but even when he brings off those seminal Fonz characteristics - the instant Greek-statuesque stare into space that is the Fonz's exclamation point, the hood-wannabe accent - he's an actor playing an actor, not necessarily a character.

Street-smart as the Fonz remains, Happy Days is a thoroughly pedestrian crossing: The ho-hum plot centers on the return of an old girlfriend (Felicia Finley) and a charity wrestling match to save the town's hamburger hangout, Arnold's. The songs are forgettable, their lyrics rarely worth a chuckle and never quite feeding the plot. Every major character gets an intro number, a sort of cliche "Hello! My Name Is . . . " label. The paint-by-numbers choreography by Michele Lynch at least moves the solid cast. Moving the show along? Another story.

At the Academy of Music, Broad and Locust Streets, through Sunday. Tickets: $25-$77.50. Information: 215-893-1999 or www.kimmelcenter.org/broadway. EndText