My first guess would be to make sure you're burning at the slowest possible speed and that you're using the Verbatim discs (Verbatim DVD+R DL AZO 8.5 GB 8x-10x Branded Double Layer Recordable Disc, 20-Disc Spindle 95310).
Also, from the DVD Nav manual it states to press the gray reset button before putting in a new version disc. If you didn't do that eject the disc, press the gray button for at least a second, then insert the disc.