It's not necessarily the discs as I've had no problems with the discs you are trying to use, but obviously they aren't working for you. We only suggest Verbatim DVD+R DL discs because the other brands are less reliable. You can see from your log what the supported speeds are for your drive/firmware/media combo, but Verbs may offer more flexibility on what you are wanting to do.
http://forum.imgburn.com/index.php?showtopic=8000