EPUB plays great in ibooks but is so huge in ADE that a letter fits on one page. Why?

I prepared a short EPUB fixed layout using InDesign CC 2014.1. It's perfect when opened in iBooks but, in ADE, the page doesn't fit. It does not display correctly, as if each page was 4 times bigger than it should. It's designed as a iPad portrait page. Do you know why this is happening? Thank you.