1) Are you sure that your dvd burner is /dev/dvdrw
Try using its actual device name, it is usually /dev/hdc.
2) Can you burn any other DVDs ?
By the time you get to using Growisofs, it should work if your DVD burner is working. Is it possible to borrow a DVD burner of someone?
Try burning a normal data dvd using Growisofs, and see if it works successfully.