You might try writing an image file first if you haven’t done that. When I first got Encore, it would not directly burn to TDK brand DVD-Rs, though it worked fine with Maxell and Verbatims. I wrote an image file first, then went back and burned the disc using the image file (still in Encore) and everything worked fine. You might have to try a different brand of DVD-R also. Some of the cheap DVD-Rs are worth less than the cheap price you pay for them.
Hope this helps. Have fun!
Rob
Rob Neidig
R&R Media Producttions
Eugene, Oregon