Halfway through “Delicate Few,” the second song of a two-hour set at Cornell University’s Barton Hall on Sunday, O.A.R. lead singer Marc Roberge told the mixed crowd of frat boys and hippies about the best advice he’s ever received from a woman.

“If you want to be up all night with me, you’ve got to take it slow,” he said.

Unfortunately for Roberge, advice that works well with his love life doesn’t work for concerts. From the opening riffs of “City on Down,” played as a slow ballad with a lengthy saxophone solo, to the closing notes of “Hey Girl” in the encore, O.A.R. never got into gear. The Maryland-based alternative rockers known for upbeat, reggae influenced jams played a surprisingly lackluster set.

Openers Grace Potter and the Nocturnals showed a much different energy level than the headliners, launching into one country/blues-influenced rock song after another. Potter showed her musical versatility, moving back and forth between her Hammond B3 and guitar. The crowd, which at first seemed slightly apathetic toward the group, was quickly won over with the band’s genre-bending performance. The climax of the nearly hour-long set was a massive drum solo featuring every member of the quartet hammering away on Matt Burr’s kit.

Sunday’s show marked the kickoff of O.A.R’s tour that will extend into the summer, and Roberge promised the crowd there would be “lots of sing-alongs.” Yet for most of the night, the group failed to bring the audience into the show. With the exception of perpetual favorite “Crazy Game of Poker,” as well as “About an Hour Ago” and “Anyways,” the crowd listened as politely as it could, with only token cheering and dancing.

Throughout the night, Roberge answered many shouted song requests from the audience with various apologies for why the band wouldn’t play a particular song. His replies ranged from “We haven’t rehearsed that, you should’ve come to us before the show,” to “We haven’t played that in two years. Maybe we’ll rock that out for you in a couple weeks.”

Since it was the first concert of a new tour, some rustiness was expected. One awkward miscommunication between Roberge and the rest of the band resulted in Roberge walking off stage right, while the band stared at him in confusion. He motioned frantically for them to begin playing, which they eventually did.

Still, diehard O.A.R. fans probably didn’t go home disappointed. Sunday’s set reached into the band’s catalogue of radio-friendly hits from earlier albums. Unexpectedly, there was nothing from the successful 2005 album “Stories of a Stranger.”

O.A.R. hasn’t had a new album since then but have still managed to (usually) please their fans with their (usually) high-energy live shows. Their most recent effort was a CD/DVD “Live From Madison Square Garden,” released last summer.

While the band’s set was uninspired, the slow-building format of the show allowed more freedom for the individual musicians to show their chops, especially saxophonist Jerry DePizzo. His improvisational solos on songs like “Black Rock,” “Conquering Fools ” and “Hey Girl” helped liven up the otherwise bland show. There were requisite solos for the other members, including guest keyboardist Mike Paris, featured in “About an Hour Ago,” and lead guitarist Richard On, whose skills weren’t really showcased until the end of the main set.

Roberge played freely with a lot of his lyrics throughout the night, substituting the traditional with improved phrases vaguely associated with love, sex, women, sex, women and more love and sex. Some of his more witty advice to the crowd included lines like  “get some loving tonight, and do it right, because if you don’t, someone else could.”