I just bought Toast and when I put the burned disc in my dvd player, it says "This type of disc cannot be played…" I'm using Memorex DVD R RW disc. Is it the disc or Toast that is the problem?

I just bought Toast and when I put the burned disc in my dvd player, it says "This type of disc cannot be played…" I'm using Memorex DVD R RW disc. Is it the disc or Toast that is the problem?

I'm using an iMac, version 10.7.5 with 2.7 GHz intel core I5 Processor. I tried using the NSTC format the first time and then I did the conversion for the second try.

Also, it freezes up. I've had to force quit Toast 3 times already.

I don't know if I picked the right community - I didn't see anything that directly addressed my problem.