Bug - incorrect numbering a file in a book

[Crimmin, Peter]

Summary:
 
Framemaker insists on incorrectly numbering a file in a book.
 
Scenario:
 
The framemaker book contains several chapters and appendices.
Add a new file to the book. For example, a 5th chapter. 
Generate the book; frame complains that numbering is different in the
document and book. Frame says it will use the book numbering.
Chapter 5 gets re-numbered as chapter 1. (When this bug strikes, it always
renumbers to 1.)
fyi, the book file is set up to continue numbering.
 
Question: 
 
Does anyone know how this happens or how to fix it? (I have a long
workaround to fix it, but want a better solution.)
 
 
Thanks for advice,
 
PeterC