Putting together a primetime lineup takes more than just throwing darts at an empty schedule. (Well, most of the time.) As the networks put together their fall plans, it's up to the scheduling executives to parse test-audience scores, research data, producer pleas and gut instincts to determine which new and returning series should make it and when they should air. But sometimes serendipity steps in, and a show will either land on the schedule or fall out of favor for unusual reasons. "Weird things happen every year," says one insider. "You think you're done, and then some crazy thing comes along." Before they sat down this week to start screening this year's batch of comedy and drama pilots, we asked a group of network-scheduling execs to share some unusual ways their programs made the grade or fell short. First impressions CSI was an afterthought at CBS in 2000, as all of the attention was lavished on a reboot of The Fugitive. There was even talk that the pilot might not be screened by execs, partly because of the dark subject matter. "There was concern about it being too gory, and it was almost written off," says one exec. But strong test results got the show on the air. How unsure were execs? Even after CBS picked it up, Disney, which originally developed the show under its Touchstone TV banner, dropped out— believing there was no chance that CSI would be worth the investment. Oops. Another show that might not have made it to air is NBC's ER in 1994. As former entertainment president Warren Littlefield recounts in his new book, Top of the Rock. Littlefield says his boss, then-NBC West Coast president Don Ohlmeyer, wasn't a fan, and the show was potentially DOA — until testing results came back, and the positive reaction was through the roof. Says another exec who was there: "Ohlmeyer hated ER. He didn't like it and Homicide was going there. [ER] was dead. Then it became the highest testing of all time." In 1996, The Pretender wasn't even initially screened at the network, but the show wound up being the highest-testing pilot since ER and that was enough to make the grade. "I believe in testing," says one exec. "It matters more than people want to admit. I do think it's a mistake not to listen to what viewers are telling you." The power of youth When ABC screened the quirky Ugly Betty in 2006, execs didn't like it. But ABC's young assistants were such ardent fans that the top brass couldn't ignore it, and reconsidered their stance.