Thanks for replying Squirrel.
Glad to hear I've done things right. I was starting to suspect I forgot something very basic but very important...
BTW, at this time I've tested on 4 home dvds more and none worked.
I'll be posting the MID of my media at lunch time, when I fire up my other computer after class. But I would say I checked the list of the DVD media they included on the modded fw and mine (verbatim MKM +R DL 2.4x certified) was there, because I see the ability to burn at 4x in DVD decrypter, as that list announced.
I have a last good idea: almost every people reporting successful DL burns used it to backup already existing DVD movies or data (XBOX and PS2) from what I have read here and on other forums. So, supossing they used DVD decrypter as that being the easiest and most reliable software to do backups, they were burning DL media using an .ISO and a .MDS files as source.
BUT that's not what I'm doing, because I'm creating my own DL discs from my own video, using TMPGEnc DVD Author. At the last step of DVD Author, I choose to create an ISO image. So I get an ISO file. Only. No .MDS at all. Then I burn that .ISO with DVD Decrypter. That's is the only difference I can find between those reporting success and me.
So: what's the information being stored on a .MDS file? it's about layer break maybe?