Topic/No book navigation appears

Error: I have an intallation of BlueSpice docu starter (v. 2.23) with bookmaker extension I installed. can create a book with articles and subarticles in the book manager. However, the navigation for the book does not appear in the Book navigation on the left navigation area. The books are listed. Clicking on a book title displays the first page in the book. No book navigation appears. Only the title of the book as a clickable link that takes you to the first article in the page."

Solution: "The Bookmaker adds tags to the pages included in the book. You may have a look at the pages included in the book, to reset the tag and insert it in the correct way you could try to save the book again. To do so go to the BookManager (via Special:Specialpages -> BlueSpice -> Book Manager), select the book needed and click on the small arrow next to the save button on the right bottom of the Book Editor. Here select “Save and add book navigation to each article” this time. Afterwards you may revalidate if the problem persists. A restart of the apache is not mandatory but may solve the problem here as well."