Conway and JM, did you not see my first post on page 2? That's not an error, and I even gave an explanation... :-(
Jazzem: levelpak.dat should be a file, not a folder. I'm not sure what you have in that folder, but it needs to be just a single set of levels...
And that is probably your problem, because you don't even have a levelpak.dat file, which CustLemm needs to have any levels at all.