Thank you very much for your reply, Doitsu ans mrmikel. I thought my post had been deleted by the moderator. I am making different chapters in Sigil and cal them: section_001_titlepage, section_002_approbatio, section_003_chaper_001, section_004_chapter_002 etc. Sigil gives no errors. When I open this file in Adobe Digital Editions I see two windows: in the right window I see my romance, each chapter starting at the top of a page, In the left window I only see: start. What I hoped to see is: start, titlepage, approbatio, chaprer_001, chapter_002 etc. So a reader can jum to chapter 037. Is that possible?
I will follow the answer of Doitsu. If I succeed I will let you know.