What to do if a child cannot narrate a particular book?

What do you all do if a child cannot narrate a particular book. My 8th grade daughter is having difficulty narrating Know What You Believe by Paul Little. I have her reading smaller chunks to help. But she consistently cannot tell me what she read. I dont think it is too difficult for her, maybe boring if she feels she already knows the material. She cannot articulate her difficulty. She is also reading Little Women, The Story of David Livingstone and Mystery of the Periodic Table which she narrates daily. She also has no trouble narrating Bible. So I think it is the book itself. Do I replace it? Do I encourage her to pay more attention? We have only recently gotten back into narrating consistently so maybe she just needs more time. Her other narrations are pretty short and sweet right now. How do you know if it is a bad book or lack of mental discipline?