A07XLA using Ulead Movie Factory, can't get 2 hours on DVD - WHY?

My Pioneer A07-XLA, using Ulead’s Movie factory Application, will not write 2 hours on a DVD. It will accept about 1.5 hours, but not any more. I like to use Movie Factory because I can take an MPG file and go all the way to the DVD creation without having to create VOB files first. The Movie Factory program does all the steps of conversion to the finished product.
I have Nero 6, but don’t I have to convert the MPG file to a VOB file before Nero will use it to create the DVD disk? Possibly using Nero I can get the 2 hours on the DVD output.
I need suggestions on the easiest way to get a full 2 hours on to the DVD output successfully.

If you cannot then probably the source is not DVD compliant - bitrate/res too high or whatever.

WHY don’t you ask the manufacturer about that?