Unable to turn page (On Mac)

Hi, I'm disapointed I can't turn pages on Digital Editions. It is very frustrating when you buy documents for university and you have to break your neck to read those documents.

I've looked at the F.A.Q., but nothing seems to answer my questioning. The solution I've find for now is to make screenshots of each pages (one by one) and then turn each image (not one by one, this time) on Preview. But unfortunately, Preview is not as great as Digital Editions to take notes.

If you have any idea that could help me, I would be very grateful.