Demi Lovato's concert tour plays Nassau Coliseum

Demi Lovato is distracted.Her tour bus parked backstage at last month's Bamboozle Festival at the Meadowlands is so close to the main stage that the thunderous guitar riffs of Billy Talent are actually rocking her ride.The 16-year-old star of Disney Channel's "Camp Rock" and "Sonny With a Chance" springs up on the leather banquette where she had been reclining and suddenly shouts, "C'mon, let's go!"It's not an act, you see. Lovato really wants to rock.