There are MPEG-4 "variations" and come variations cause trouble with some software...
There are work-arounds, but
I'd try to return the software since it doesn't work "as advertised". I believe you have that right in most jurisdictions even if there's a policy of "no returns on opened software".
When I run into a "problem format", I convert it to DVD-compatible MPEG-2 with
SUPER (FREE!!!). But, for me it's an occasional thing... I'm not stuck with a camera & software that don't work together.

(Maybe the software that came with the camera will allow yout to convert to a different format?)
I don't know much about the "Express" version, but it wouldn't cost you anything to download & try the trial version of
Video Studio Pro.
Before you buy ANY more software, I recommend you download the trial first! 
There are too many audio/video formats & format variations, and the whole situation is a royal mess!
