• by Wayne Friedman , March 12, 2010

NBC's efforts to lure back later-evening viewers continue to be an uneven affair.

Moving "Law & Order: SVU" back to a 10 p.m. time period on Wednesday seems to have been the big winner so far; "Parenthood" on Tuesday also seems competitive.

But the original "Law & Order," now Monday at 10 p.m., didn't register with viewers, coming in at a distant third place. And now the Jerry Seinfeld-reality effort "The Marriage Ref," settling into its regular Thursday 10 p.m. time period, seems to be losing steam.

The "Ref" -- which got a good start, thanks to the lead-in of the Olympics -- has now sunk some 21% this week to a Nielsen preliminary 2.6/8 among 18-49 viewers, landing in third place just behind "Private Practice" (2.9/8), and CBS' "The Mentalist" (3.4/10).

NBC, which did so well a week ago on Thursday, suffered with virtually all its comedies. "Community" was down nearly 20% to a 1.9/6; "Parks & Recreation" slipped about 10% to a 2.1/6; and "The Office" fell almost 20% from its big "baby" episode a year ago to a 3.8/11.

Two bright spots here: "The Office" remained in a virtual tie with "Grey's Anatomy" at a 3.8/10. Last week for the first time, an original episode of the "The Office" beat "Grey's" in its 9 to 9:30 p.m. half hour.

Lots of other shows were down as well, including another special Thursday edition of "American Idol," off 5% to a 6.3 rating/18 share among 18-49 viewers. Still, "Idol" was easily the best-rated show of the night, giving Fox another solid Thursday night victory.

CBS was off 5% with "Survivor: Heroes versus Villains" at 3.6/11 during the 8 p.m. hour. But its 10 p.m. show "The Mentalist" was up some to a 3.4/10.

ABC was up and down as well. "Grey's Anatomy" was down 3% to a 3.9/11 for the hour, but "Private Practice" was up 7% to a 2.9/9.

For the night among key 18-49 viewers, Fox was at a 4.7/13, CBS, a 3.4/10, NBC, a 2.7/8; ABC, a 2.6/8, Univision, a 1.3/4 and CW (in reruns) at a 0.5/2.