Some types of media need to be formated before use.
I don't have 1st hand dvd experience but maybe formatting would solve
your delima.
how exactly would you go about formatting a dvd-r? i don't think thats possible.
chances are the dvd burner is -r. also, some dvd media just won't work with some dvd burners. it happens. if you can, i'd take the stack back, or sell them on ebay or something. I bought some cheap dvd-r's once, and my drive wouldn't recognize them either.