Dvd burner won't burn

I am Having trouble burning dvd's. The player will ask to format the new disk and then complete the formatting process, and then I will try to record a t.v. show and it will spit the disc back out and say unknown disc in the player. It plays regular movies and cd's with no problem so it does work on playback mode. The blanbk dvd-rw's are a name brand tdk so I don't know if there is something wrong with the player.Please help