I used it recently with no problem. Only 1 CD though, with 23 individual tracks.

It would be helpful if the website told you what the problem is, but how often do they do that? Have you numbered all the tracks correctly? You have to provide numbers for the CD, track number, the medley, and the individual tunes comprising the medley, and it can get a bit confusing. I imagine an error in the numbering might cause it to be rejected.