I'm New and I Need Help!

I’ve just purchased a Pioneer DVD-R 104 drive and I don’t appear to be having any problems writing. When I try and play a movie in my set top box (Pioneer 717) I keep getting blocking at the end of the film any idea’s?

I’m using Traxdata discs? Is it because I’m using cheap media?

Also what is the best media to use I’ve just ordered some TDK disks?