IVONA TTS problem

I've tried this feature on the T68, using headphones, on a couple of books previously purchased from GooglePlay, and it always stops after reading one sentence or sometimes one paragraph. I hear a low click, and it then turns off. I purchased and downloaded a voice from ACAPELLA, and this works fine, and automatically changes pages while reading. Is there any way to adjust the settings for IVONA so it reads correctly?
It's not a feature I plan to use often, but it comes in handy for me sometimes.