How can I make sure that the last word in the text on a page is highlighted and the Audio plays at full length?

When I play my read aloud text, the last word of the Audio file is cut of. When I use the read aloud tool an tap for every word, after the last word of the Text Pubcoder gives me an "end" to tab on. I always paused to press this finish button, so that the audio would not be cut of, but this had the oposite effect. But when I push it to soon, same effect. The Problem does not show in the preview, only in the final EPUBon the iPad, and not on every page. Therefore, at some pages I must have done something right, but don't know what it was.
Also, the last word is not always highlighted, and I don't know when or why.
Please help, I am desperate! Thank You!
(Word by word highlighting is very exhausting..)