NBC has extended a full-season pick-up to “Out All Night,” the first-year sitcom starring Patti LaBelle and Morris Chestnut, committing to a total 22 episodes on the NBC Prods. series.The show, which started in a Saturday slot, moved last week to Thursday, where it premiered with an inauspicious 9.0 rating, 14 share. The show averaged an 8.1/15 for its Saturday airings. Still, NBC is saying it intends to stick by its series instead of thrusting new shows into difficult time periods where they’re virtually destined to fail. NBC has given full-season orders to new Sunday shows “Secret Service” and “I Witness Video” (produced in-house through NBCP and the news division, respectively) and to the TriStar TV comedy “Mad About You.” Meanwhile, NBC and Lorimar TV are launching what looks to be a last-ditch campaign touting acclaimed but low-rated drama “I’ll Fly Away,” with ads in newspapers Friday saying “Tonight, you can make a difference,” urging viewers to “save this show.” NBC back-up series include the dramas “Crime and Punishment,”"Homicide” and “Route 66″ and the sitcom “Almost Home,” a re-worked version of “The Torkelsons.” Another comedy, Jay Tarses’ “Smoldering Lust,” may be held to air as original summer programming.