Why aren't they showing this on ABC?

Ratings. ABC, unfortunately, is not willing to give it a chance. The time slot (opposite Mad Men and Curb Your Enthusiasm/Entourage) was horrible to begin with. The premise of the show is such that it would have been better off being on the scifi channel, where there is less pressure to get high ratings. I actually think DG is better than ALOT more than half of what's on tv. Better, in fact, than Flash Forward, which was (and is) given a heck of alot more support by ABC than DG ever was.