No DVD Error

Ok, I have the Sony DWD22A (OEM) drive. I have Ridata 8x DVD-R discs, and the latest version of Nero 6. Everytime I try and burn something to a dvd disc, it spits out my disc and says please insert disc. (While on the screen it says the drive is empty…) Nero recognizes the drive, and the drive plays DVD’s ok. I’m thinking its the media, but I don’t know why there would be any problems… Please help!!!