How can I make 'Talkback' really talk in a Samsung Galaxy S3?

[Tania Pintilie]

Hi there, I've just bought my Mom who's visually impaired a Samsung S3 and I've got trouble making it speak. When I turn the 'talkback' on it whows me te text of what it should speak outloud on a red background on the bottom of the screen, but it doesn't actually say anything. I checked the volume and I tried choosing either Google mode of Samsung mode in 'text to speech options'. I'd appreciate any advice. Thanks a lot.