Why dont my dvd's and cd's made with Ashampoo work?

I am using the Ashampoo burning studio 10 Trial version and it says that i have no limits to using it for 30 days. So i have burned videos on to a dvd and finalized the but it wont play on my dvd player. My dvd player is really a DVD recorder but it is suppposed to play dvds and cds also. I dont know if this could be why or not, but the videos im burning are flv. Thank you for all your answers!