Problem burning DVDs

uh hey im mike, new here just looking for some answers. i just want to know why i can burn cd’s but when i try to burn a dvd it encodes it then tells me that i cant burn it and i was wondering if im even doing it right in nero. ive never had this much trouble but i got an external sony burner, drx-820U i need to figure this out they are downloaded movies BUT i can assure they are for home use only…HELPPPPP :a

If you are going from XviD/DivX to DVD then the filesize will increase dramatically. It’s possible that it’s over the size for a single layer DVD.