Here's what it comes down to, Nexgen is looking for information in a particular form and fashion...as I recall...Nexgen could be configured to look for data in particular "ranges" and fields within the print file...totally user configurable.
Along those same lines, if your music scheduler print to file settings are configurable...just figure out what fields you want/need and setup Nexgen accordingly.
Of all the automation systems I've ever used, Nexgen was probably the easiest and least picky about print file formats for loading logs: file number, date/time for each event (don't think that's even necessary), and a corresponding system (1-99) number that tells NexGen what the file is...or what command you want it to do in what spot (fade n' go, switch to manual, auto, etc...check your manual) ...then artist, title, length. My memory is hazy. It's been 5 years since I worked with NexGen.
That said, if you're using some off brand of music scheduler, I highly suggest looking into a download of the musicgen music scheduler...it's designed to work with nexgen, and it's better than most cheap schedulers. You might be able to find a free download of musicgen somewhere on the internet...it was a free program for quite a while. Since I don't know what you're using now...I just thought I'd throw that out there.
Lastly, doesn't matter if you're using selector or other brand name schedulers, or AudioVault, or SS32...getting logs to print and import just right into an automation system can be highly frustrating. It's frustrating, too, from a support standpoint. Good luck. Hope something here put you in the right direction.