It’s oddly earnest, this dim and measured staging by Mark Waldrop. Everything is cautiously functional, from James Fouchard’s drab fake-brick set for the Skid Row flower shop to David Kaley’s only slight tacky costumes for Seymour and Audrey, the bruised and mousy beauty he adores. It’s almost as if Waldrop actually believes the story and wants us to treat it as real.

The humongous plant puppet singing and gobbling up the cast (this is ultimately a sci-fi saga of intergalactic domination) tells you otherwise, of course. But so does the music: “Little Shop” is an exceptionally witty goof cooked up by gifted songwriters in their salad days. Ashman, who died in 1991, went on to write Disney’s “Little Mermaid” and “Beauty and the Beast” with Menken, and they spoofed 1960s music with real affection here. The catchy choral “Skid Row,” the gloriously silly love duet “Suddenly Seymour,” and those shang-a-lang-lang phrases from the ever-present girl group: that’s the heart and soul of the show.

Yet music is hardly the strength of the Olney’s production. The small pit band is muffled and the singers are often overbearingly overmiked; if the Olney is going to continue producing a couple musicals a year, someone ought to figure out how to create alluring sound each time out. Nobody moves with verve, either, despite the dance-ready beats of Menken’s score.

So numbers that ought to soar just go phhht. Bobby Smith, one of the savviest musical actors in town, is stranded as the sadist dentist during his two songs, “Be a Dentist” and the particularly awkward “Now (It’s Just the Gas).” Carolyn Agan, breathy and delicate as many an Audrey before her, is guided to take Audrey’s puckish ballad “Somewhere That’s Green” at such a lugubrious tempo that a kid in the back row could be heard whispering during a pause, “I don’t like it.”

Ford’s Theatre ran into the same sort of wall with “Little Shop” two years ago; the production somehow seemed preoccupied with the meaning of the show’s story. In a musical, though, especially the fun ones, the story is an excuse for the crafty songs — not the other way around.