My problem was the screwdriver not engaging on the white wheel that is down in the adjustment hole. 20 turns would definitely give you movement. I had to angle the screwdriver so the head was pressed to the white wheel and make sure it was rotating after I leveled mine. And of course I was in the dark too...
2010 FX4 SCAB tuxedo black loaded, Bilstein 5100 Leveling Kit, K&N Series 63 Aircharger CAI, Corsa dB Catback Perf Exhaust, HD/Raptor Head and Tail swap, T-Rex Full Billet Grille (Black Powdercoat), KC HiLites Lightbar, 2 KC HiLites 135w Long Range 6" Daylighters (285k Candlepower), 2 KC HiLites 135w Driving Pattern 6" Daylighters (175k Candlepower), Westin black tail light guards