content of DVD disappear (but reappear...sometimes)

I copied/saved a movie on a blank DVD+R and I verified personally if everything is OK. Then I put it away.

I copy the movie by simply putting a blank DVD in the tray and then opening "File-->New Burn Folder", moving the folders in there (the movie has 20 folders one for each episodes, but I can only put 5 on 1 DVD).

In the past I used Toast titanium but since I upgraded to Mountain Lion 90% of my blank DVD receives an error. So I stopped using it.

Here's the problem: I put the DVD in the computer and the disc appears on the desktop with the name "Untitled" instead of "I need Romance 1-5" and if I open it, there's nothing there! It's empty.

I try again, same thing, I try again (because I know it's OK, I verified it myself) and this time it appears with the name and it contains the 5 folders "I need Romance 1", "I need Romance 2", etc.

But I needed to try 3 times, sometimes 4 times before it appears the way it should.

My question is why does this happen?