Issue with Burning onto a DVD+R DL Disc

I have never successfully backed up any of my music/data files onto the blank DVD+R DL (8.4GB) discs I purchased (a 25 pack too $$$).
I have used iTunes and Roxio (came with my SZ-110). The process begins but then it stops and spits the DVD out. I do know that the max rate is 2.4x. But still nothing. SONY said I should try using a SONY branded disc, but I doubt that will work, even if I find individual ones to buy since theres no way Im buying another 30 pk. I did buy a 3 pack of DVD-RW @ 4.7 GB and that worked well along with the regular CD-Rs. Just have the issue with DL discs. I dont know if these programs dont support them, even though they recognize the type of disc and available space left. Or is it the driver for the dvd-burner, even though like I said a DVD-RW worked well. I havent seen many complaints regarding this nor any updates regarding this issue on my model page at sony support.

 

My starting point would have been the same as Sony's - try another brand of disk. Doesn't necessarily have to be Sony branded and you could just buy the minimum amount possible just to test it out. That's what I would do before I started blaming firmware or applications. The fact that it failed in both iTunes and Roxio would lead me to believe it might be the media, especially if it they both work fine with other DVD-RWs and CD-Rs.