What are the best cds to use with a sony dvd/video recorder?

I have bought maxell dvd-rw and -r and both dont work. In the book it says that i can use 1x or 2x -r and that is what i bought but it is still not working. When i first bought the dvd recorder it worked just fine with the -rw of any kind now it wont record on any disk. I want to be able to re-record but i am wondering if there is something wrong with my dvd player its only a few months old.