Having problem burning DL DVD with Nero

I have a couple Dvd’s that I used DVD decrypter and have the 7.0 gig files in video ts. I tried to use nero make a dvd video feature and dragged all the files to be burned. WHen I click burn it says insufficient space on disc. This is not true I put in an 8 gig disc and the graph that shows you space is not even in the yellow. Then it asks for a DVD DL disc and I put in a Nextech DVD+DL. It still wont burn any ideas?

Try better media

I thought it might be the cheap disc. Because drive seems to take a long time to read disc. Im pretty computer savvy and if it say insert dvd dl and I insert a DVD+DL it should work