DVD-Lab not recognising MP2 audio stream

[gsh]

I am attempting to re-author a DVD of a tv show. I want to have the whole show as one project, just certain parts of it (interviews) as another project, and a bonus as a thid project. The DVD is already authored as one project, so I decided the easiest way was to rip the bits I want as the second project as one combined file from the chapters. In order to do this I had to re-do the chapter points, which I did ripping with DVD Decrypter minus the last 3 chapters and re-authoring with IFO Edit, then burnt it to disc. I then demuxed the interview chapters I wanted. When attempting to import the audio into DVD Lab, I get the warning
DVDLab expect the mp2 file to be an audio file - Your file is not recognised as audio - Some software such as Pinnacle name their videos mp2 and they have to be renamed to mpv and imported again.
I am not given the option to ignore the error. I checked the audio file and it plays no problem in WinAmp.
I then checked each chapter by demuxing and importing the audio, and I get the same error for all except chapter 1. The audio file for the whole program imports no problem, which was ripped from the same disc. The last 3 chapters that were ripped from the original disc demuxed and the audio file imported okay.
I then attempted to import the vob of the interviews, but during demux DVDLab gave another warning,
Bad header or unknown error - This file doesn't seem to be Mpeg audio - check if it is a wrongly named ac3
So I finally tried importing the whole show into DVDLab to re-author and burn, to see if it was some kind of incompatibility with IFOEdit. I get the same errors with the files demuxed from a DVDLab authored project.
I'm at a bit of a loss now, so any help would be much appreciated.
I'm using DVDLab v.1.3 and DVD Decrypter v3.2.3.
Thanks

[troyvcd1]

Ifoedit is messing up your audio file.

[gsh]

I don't think it is IfoEdit - I tried re-authoring the files from the original disc in DVD-Lab (ripped with Decrypter), then ripped and imported the chapters from that, but got the same error.
My workaround has been to download and use DVD-Pro beta and use the branching feature. It's worked fine, but I am still curious as to the original problem.
As a sidenote, dbPowerAmp recognised and converted the troublesome mp2 to wav no problem!