Epub conversion problems from CHM

[Chrisness]

Hi,
I have 3 books in CHM format; all three with at least 3000 pages in each... First book went fine with no problems to convert into Epub and the other two books work fine as well, ALTHOUGH the other two books will only contain the preface, introduction, acknowledgement etc and then skip the rest of the CHM file containing the actual content (??) how come this?
Is it possible to fix in any simple way?
When I watch the 2 books in the CHM format I can see that the first introductory files are linked wit doted lines ("connected") with the rest of the files (part1, part 2, part 3 etc etc etc etc...) So is not the case in the first book. Could there be a link there?

Would really appreciate some kind help
/Chris