Thanks for your help. I've set the booktype on other DVD burners. The booktype changes the default booktype of DVD+R to DVD-ROM. In the lower right hand corner of the ImgBrn GUI there is a small icon that looks like an open book or you can use the method you describe. In either case you must select a/the tab that corresponds to your drive, i.e. Plextor Ricoh, Samsung, BenQ, LG, LITE-ON, NEC or NuTech. I don't know what HL-DT-ST corresponds to. I have tried all the available tabs, but the command fails.
Thanks again, Garyflyer