Did you burn it as a DVD9 or DVD5? DVD9 is for dual layered dvds and players (approx. 8 gig). Nero, I think, defaults to DVD9. If your DVD player is not a dual layered compliant player, it won't read DVD9 burns, even if the burn was on a DVD5 (single layered) dvd.
I just acquired Nero 6.6, and I just figured that out after burning 2 coasters.