It could be that the particular DVD-R blank you used was defective, or the brand you're using is poor quality
This is probably not the case since the media used was the same in both ocasions (PRINCO. Tried with Lg after first drawback and it didn't work either. DVD-RW is maxwell). I think maybe the problem is with growisofs. I know that with DVD-RW it engages DAO (disk at once) burning, which is the best method for DVD-Video burning; but on DVD-R it does Incremental Sequential burning. There are some caveats with this process and it does not ensure maximum compatability for DVD-Video. But, like I said before, I did the process a year ago and it worked. Just can't figure out why it isn't working anymore.
By the way, I tried to use cdrecord.ProDVD since it can perform DAO DVD writing. Unfortunately, cdrecord works when it wants on my system (even non-DVD version) and I lost a couple of medias with it. Couldn't finish one single write (some SCSI error).
For the record, a have a Lg DVD-GMA 4020B DVD writer