Why is it when I burn a DVD with a DVD authoring program like Sonic DVDIt or Pinnacle, I can't scan fast forward or scan rewind it with my Apex 500W, but when I copy a DVD with DVDXCopy, I can?

I used to think that the Apex just couldn't scan with the DVD-R media, but I use the same blank media when using DVDXCopy, and it works fine.

Any thoughts?