mcdedit

I have tried everything for 3 days to export a completed, edited video in all possible formats using the latest Videopad program V 7.30 Professional which plays perfectly on the edit screen. Having saved and exported, on playback, all I get is a black screen, and in most playback programs about 1-2 secs of black screen from a 3minute.50 clip . This seems to have been a problem for years in many versions. How do I get resolution as I have waited for tech support for several days ? Under Australian law, if a program does not work as advertised a full refund is mandated. I would prefer resolution.