I own a Tevion DVD

Question

I own a Tevion DVD recorder TDR5101. It will play commercial DVDs and I can record on the DVD which was supplied with the equipment. When I try to record on a Sony DVd R (RW) I get an error message on the DVD, or it says load and then nothing happens. I have to switch off the DVD and then switch on again in order to open the player and remove the disc. I am not sure it this is a fault with the machine, or whether I using the wrong sort of DVD. Hope you can helpMany thanksMarjorie