FM8 + DITA: Cannot create a book from a map.

Hello,

I want to create a book from a map with the standard FM function.

1. Do I reference .xml topics? I read something about .fm.xml topics? How can I get this file format?

I reference topics in the file format xml. If that is not right please ignore my other questions.

2. I can create a document from my map without any problems. When I create a book from the map I get the following
xml read report log that I do not understand:

a) Cannot insert a marker in the book.

b) Ignore the text that was encountered in a book.

c) Cannot insert the FM element (ul) in the specified location in the book.

With kind regards

Nina